Allah, the Wise, has said:
قُلْ جَآءَ الْحَقُّ وَ زَهَقَ الْباَطِلُ اِنَّ الْباَطِلَ کاَنَ زَهُوْقاً
"And say: The truth has come and the falsehood has vanished; surely falsehood is a vanishing (thing)." 
Imam Ali (as) said:
ظَلَمَ الْحَقَّ مَنْ نَصَرَ الْباَطِلَ.
"One, who helps falsehood, has oppressed (and done injustice to) the truth." 
There are several levels to comprehending truth and falsehood, and individuals differ vastly with respect to acceptance and rejection of them. The general rule, with regards to the truth, is that the heart should be inclined towards Allah, His commandments and the realities, while the rule with regards to falsehood, is that the heart should be averse to things that are prohibited and related to other than Allah, and the interior should be kept away from dirty and impure carnal attachments.
A pious person comprehends that falsehood weans a person away from realities and it shall cease to exist, and it is only truth, which is deep-rooted and continues to exist. Thus, one must adhere to the people of truth and stay away from the people of falsehood.
1 – The Right of a Deceased Muslim
Zurarah relates: I was in the company of Imam Baqir (as) in the funeral procession of a person from Quraish. Ata, the jurist of Makkah, was amongst those present in the funeral procession. Suddenly, the air was filled with the wailing of a lady. Ata instructed her to remain quiet as otherwise he would have to turn back. But the lady continued to wail and so Ata left the procession.
I informed the Imam (as) about Ata's turning back.
"Why?" inquired the Imam (as).
I replied, "Due to the lamentation of a lady. He asked her to keep quiet and when she did not, he left."
Imam Baqir (as) said, "Stay with me and we shall accompany the deceased. If we notice falsehood together with the truth and forsake the truth due to that falsehood, we would not have fulfilled the right of the Muslim." i.e. escorting the funeral of the Muslim, which is his right, should not be forsaken for the sake of the wailing of that lady (which, according to the non-Shi'ite sects, is forbidden and prohibited).
When the prayers were offered for the dead person, his relative said to the Imam (as): "May Allah have mercy upon you! You can turn back for you do not possess the strength to walk." Imam (as) continued to accompany the funeral procession.
Zurarah continues: I said to Imam Baqir (as), "The relative of the deceased has permitted you to turn back."
"If you have some work, you may go," said the Imam (as). "I have neither come here with his permission nor do I need his permission to return. I have come here to seek the rewards, since man shall be rewarded in the measure in which he accompanies a funeral procession." 
2 – Mua`wiyah Ibn Yazid
After the three-year Caliphate of Yazid (who brought about the murder of Imam Husain (as)), the lootings and crimes in Madinah and sacrilege with respect to the Kaabah, the Caliphate reached his son Muaawiyah. Whenever Muaawiyah slept at night, two slave-girls would remain awake, one near his head while the other near his feet, in order to protect him from inconveniences.
One night, thinking that the Caliph was asleep, the slave-girls began conversing with each other.
"The Caliph likes me more than you and if he does not set his eyes upon me three times a day, he gets restless and disturbed," the one that sat near the Caliph's head said.
"Hell is the abode for both of you," commented the other slave-girl.
Not being able to sleep, Muaawiyah heard the conversation. Predictably, he felt the urge to get up and put the slave-girl to death, but he controlled himself and waited to hear more of their dialogue.
The first slave-girl wanted to know why the second one had made that remark. She got the following reply: "Muaawiyah and Yazid, the grandfather and father of this Muaawiyah, were the usurpers of the Caliphate, since the rank was the right and privilege of the household of the Noble Prophet (sa)."
When Muaawiyah heard this, he drifted into deep reflection and finally made up his mind to step down from the false Caliphate and inform the people of the true leader.
The next morning he ordered all the people to be present in the mosque. When the mosque was full, he ascended the pulpit and after praising Allah, said: "O' People! The Caliphate is the right of Imam Sajjad (as) whereas my grandfather, my father and I were its usurpers."
He descended from the pulpit, returned to his house, locked himself in and refused to allow anyone to enter it. When his mother was informed of the incident, she approached him, beating her head with her hands.
"Oh! How I wish that you had been the blood of my monthly cycle so that I might not have had to witness such an act from you!" she shouted.
Muaawiyah remarked, "By Allah! I wish I had been just what you desired so that you had never given birth to me!"
For forty days he did not emerge from his house. In the meantime, Marwan Ibn Hakam took over the reins of the Caliphate. Marwan then married Muaawiyah's mother (Yazid's wife) and a few days later he had Muaawiyah poisoned.
3 – Accepting the Truth
One night, Saaid Ibn Musayyab entered the mosque of the Noble Prophet (sa) wherein he observed a person offering prayers. He was reciting them in a loud and beautiful voice. Saaid instructed his slave to go to the person and request him to recite his prayers softly.
"The mosque is not our property; this person has a right over it too," the slave said.
Saaid decided to do it himself. He called out in a loud voice: "O' Worshipper! If you are offering your prayers for Allah, then lower your voice, but if you are offering it for the people, (then do realize) they shall not benefit you in the least."
The person, appreciating the truth in this advice, lowered his voice and recited the remainder of the prayers in a low voice. As soon as he had completed his prayers, he picked up his shoes and left the mosque. After he had left, it transpired that the person was aUmar Ibn Abdul Aziz, the ruler of Madinah.
4 - The Intoxicated turns Grateful
Dhunnun Misri relates: "I had come out of Egypt for a walk and was strolling along the banks of the river Nile gazing at its water, when I suddenly caught glimpse of a scorpion moving forward hastily. I wondered where it was heading. As it reached the riverbank, a frog surfaced from within the water; the scorpion climbed onto its back and the frog began to swim through the water. "There is something mysterious about this event," I thought to myself. I jumped into the water and began to swim after them.
I observed that when the frog had reached land, the scorpion got down from his back. I continued to follow the scorpion till I reached a tree. There, I found a youth lying in its shade. Beside him was a black snake that was about to bite him. Suddenly, the scorpion rushed forward and stung the snake in the back. The snake died instantly.
After this, the scorpion proceeded towards the water, climbed onto the frog's back and was ferried to the other side. I stood absolutely amazed.
"This person is surely one of the auliya (close friends) of Allah!" I whispered. I was about to kiss his feet when I realized that the man was intoxicated, and this only served to add to my amazement. I waited patiently for the youth to recover from his drunken state and when he regained consciousness, he saw me standing near him.
"O' one, who is the leader of his time! You have come near this sinner and honoured him," he exclaimed in astonishment.
I told him to leave aside the rhetoric but to look at the snake beside him. Seeing the snake near him, he slapped his forehead and inquired what had happened. I related to him the entire incident of the scorpion, frog and the snake. On hearing about this and observing the grace of Allah upon him, he raised his head towards the heaven and cried: "O' You! If Your grace upon the intoxicated ones is in such measure, how much would it be upon (Your) friends?"
Then, after performing ablution in the Nile, he turned towards his house. From then on, he engaged himself in self-rectification, till he reached such a stage and rank that every sick person for whom he prayed would become cured."
5 – The Gratitude of Abu Dharr
When Abu Dharr received the news that a Prophet had manifested himself in Makkah, he instructed his brother Anis to go and acquire some information about him.
His brother went to Makkah, came back and described the Noble Prophet (sa) to him.
"You have not been able to smother the flames that smolder within my heart," Abu Dharr complained.
He therefore made arrangements to undertake a journey to Makkah. On his arrival there, he took shelter in one corner of a mosque till on the third day, under the guidance of Ali (as), he covertly approached the Noble Prophet (sa) and greeted him.
When the Noble Prophet (sa) asked him his name and inquired about him, Abu Dharr gave him the answers, following which he accepted Islam.
The Noble Prophet (sa) advised him: "Return to your city and do not stay in Makkah for I fear that you might be subjected to persecution (here)."
"By He, in Whose Hand lies my soul! I shall shout out in front of the people and loudly proclaim my acceptance of Islam," responded Abu Dharr.
He headed straight towards Masjidul Haram where in a loud voice, he testified to the Unity of Allah and the Prophethood of the Noble Prophet (sa). Hearing this, the people of Makkah rushed towards him to beat him up till he dropped down, unconscious. As Abbas, the paternal uncle of the Noble Prophet (sa) witnessed the scene, he threw himself upon Abu Dharr and shouted out to the people: "O' People! Woe unto you! Do you not see that this person is from the tribe of Ghaffar and was amidst you while on a journey towards Syria?" With these words, he managed to save Abu Dharr's life.
The next day, his condition improved but Abu Dharr again proclaimed his new faith and was badly beaten up once more. For the second time in as many days, Abbas intervened and saved him from their beatings. After this, Abu Dharr left Makkah and returned to his city.
 Noble Qur'an, Suratul Isra (17), Verse 81
 Ghurar al-Hikam, Tradition 6041
 Ba Mardum In Guneh Barkhord Konim, Page 55; Al-Kafi, Volume 3, Page 171
 Dastan-ha Wa Pand-ha, Volume 9, Page 154; Jamea al-Nurain, Page 316
 Shanidani-ha-e-Tarikh, Page 18; Mahajjatul Baiza, Volume 2, Page 230
 Jawamea al-Hikayat, Page 46; Siyar as-Salihin
 Paighambar Wa Yaran, Volume 1, Page 45; ھayan al-Shiaa, Page 316