Allah, the Wise, has said:
يَا أَيُّهاَ الَّذِينَ آمَنُوا لاَ يَسْخَرْ قَوْمٌ مِنْ قَوْمٍ
"O you who believe! let not (one) people laugh at (another) people." 
The Noble Prophet (sa) said:
مَنْ حَقَرَ مُؤْمِناً مِسْکِيناً أَوْ غَيْرَ مِسْکِينٍ لَمْ يَزَلِ اللٌّهُ عَزَّ وَ جَلَّ حَاقِراً لَهُ مَاقِتاً.
"If a person humiliates a believer, indigent or otherwise, Allah shall always abhor and humiliate him." 
Factors such as arrogance, malice, envy and the like cause some individuals to view others who are either illiterate or lack strength and whom they have compelled into performing base and lowly work, with contempt and humiliation.
Disparagement in every form is forbidden; moreover, if the humiliated person experiences a feeling of disgrace and injury, this is bound to result in a metaphysical reaction which would reflect badly upon the esteem and personality of the offender. Thus, it is befitting to take regard of the weakest of Allah's creations so that, we too are encompassed by His grace and compassion.
1 – Mufazzhal Ibn aUmar
Once, a letter signed by some of the Shiite elders, was brought to Imam Sadiq (as) by a few of the signatories themselves. The letter complained of the friendship of Mufazzhal Ibn aUmar, the Imam's representative in Kufah, with some pigeon-fanciers, who were apparently not of good character.
After reading the letter, the Imam (as) wrote and sent a letter to Mufazzhal through those very individuals who had brought the complaint to him.
Perchance, the Imam's letter reached Mufazzhal while some of the signatories of the letter of complaint were present in his house.
Opening the letter in their presence, he read it and then handed it over to them. When the signatories read the letter, they found that it contained some instructions from Imam (as) to Mufazzhal, requiring him to arrange a transaction involving a large amount of money. The letter did not make the slightest reference to Mufazzhal's association with the pigion-fanciers.
Since the issue concerned the raising of money, Mufazzhal's guests lowered their heads and said that they needed time to think about it. They asked to be excused from making any monetary contribution.
Mufazzhal, the intelligent person that he was, requested them to stay over for food and prevented them from leaving his house. In the meantime, he sent word to the pigeon-fanciers asking them to come to his house. When they had arrived, he read out the Imam's letter to them in full view of the previous group. Without wasting any time, the pigeon-fanciers left and while the previous group was still engaged in consuming the food, they returned, handed over a large amount of money to Mufazzhal and then took his leave.
At this point, Mufazzhal turned to the complainants and said: "Despite the fact that these youths help the religion when the occasion demands and there exists a great possibility that they may turn to the right path, you desire that I should not entertain them and associate with them? Do you think Allah is in need of your prayers and fasts that you have become so haughty over them, but when it comes to money, you seek excuses and refuse to answer the call of the Imam (as)?"
The elders who had viewed Mufazzhal's friendship with those youths with contempt, were left mortified and speechless as they departed from his house.
2 – The Conduct of the Noble Prophet
The Noble Prophet (sa) and a few other individuals were having their meal when a person, suffering from smallpox, came to the gathering. His disease was so acute that the boils had become septic. Every person, near whom this diseased person tried to sit, would show his revulsion and loathing by rising up and moving away from him. (Noticing this) the Noble Prophet (sa) made the person sit beside himself and exhibited great kindness towards him.
On another occasion, the Noble Prophet (sa), together with a few of his companions, was busy having his food when a leper arrived in the gathering. The people present expressed their abhorrence and detestation over his arrival but the Noble Prophet (sa) asked him to sit next to himself and invited him to eat the food.
A person from the Quraish, who had displayed his aversion, was afflicted with the same disease before meeting his death!
3 – The Consequence of Holding Someone in Contempt
There lived amongst Bani Isra`il, a person who was so sinful and immoral that they eventually had him expelled from their midst.
Once, while wandering around, he came across a pious worshipper, above whose head flew a pigeon casting its shadow over him (thus protecting him from the sun). He said to himself: "I am a Banished person but this man is a pious individual; if I sit near him it is possible that due to his piety, Allah may show mercy upon me too."
With this in mind, he approached the worshipper and sat down beside him. On seeing the exiled man sit next to him, the worshipper thought to himself: "I am the pious worshipper of this tribe whilst he is a disreputable, Banished and despised sinner; how can he sit down beside me?" Turning his head away from the man, the worshipper ordered him to go away from him.
Just as he had uttered these words, Allah revealed to the prophet of the time: "Go to those two persons and ask them to start their deeds afresh, for I have forgiven all the sins of the immoral person and erased all the good deeds of the worshipper," (for exhibiting self-conceit and holding the other person in contempt).
4 – The Short and Ugly Son
Saadi narrates: "A king had several sons, one of them being short, thin and ugly, while the others were tall and good-looking.
The king would look at the short son with scorn and contempt, thereby causing him humiliation. The son, being intelligent, realized why his father looked down upon him and so said to him: "O' Father! A short but wise person is better than a tall but ignorant one. He who is taller is not necessarily better and superior; a sheep is clean but an elephant, like a carcass, always possess a foul smell."
The son's words made the king laugh and the elders of the court approved of what he said, but his brothers were upset.
Coincidentally, during those days, it so happened that the enemy forces attacked the kingdom and the first person from the king's army to heroically attack the enemy was the king's short and ugly son. With a display of great courage, he felled a few of the enemy chiefs and then, returning to his father and paying his respects to him, said: "On the day of battle the lean horse comes of use."
Despite the fact that a group of his soldiers had taken flight, the son returned to the battlefield.
"O' Men! Endeavour hard or else put on the dress of womenfolk," he shouted with bitter sarcasm.
This sarcasm breathed fresh life into the cavalry who fought with renewed vigour till they eventually overcame the enemy forces and became victorious. The king kissed his son all over the face and named him his successor. From then on, he looked at this son with great respect and esteem. These events caused his brothers to become so envious of him that they put poison into his food in order to get rid of him. Fortunately, his sister watched what was happening through a small door and sent a warning signal to her brother by shutting the door loudly. The intelligent brother became suspicious and abstained from eating the food.
"It is impossible for skilled people to die while the unskilled ones continue to live on and take their place," he commented.
When the king was informed of the incident, he reprimanded the other brothers and sent each of them to the farthest part of his kingdom.
5 - Bring forth One Worse than Yourself!
Allah revealed to Prophet Musa (as): "The next time you come to converse with Me, bring along someone who is inferior to you."
Musa (as) set out in quest of such a person but failed to find one, because every person that he encountered, he did not have the nerve to think that he was superior to that person.
Then, deciding to direct his search amongst the animals, his eyes fell upon a diseased dog. He decided to take it along with him. He tied a rope around the dog's neck and began pulling it but after a short distance, he regretted his action and set the dog free. He returned empty-handed to have his conversation with Allah.
"Why did you not bring someone along with you, in accordance with My order?" came the voice from Allah.
Musa (as) beseeched, "O' Lord! I failed to find anyone who could be inferior to me."
The reply came from Allah: "By My Might and Glory! Had you brought someone, regarding him to be inferior to yourself, I would have surely erased your name from the list of Prophets (and relieved you of the rank of Prophethood)!"
 Noble Qur'an, Suratul Hujarat (49), Verse 11
 Jamea al-Saaadat, Volume 2, Page 215
 Ba Mardum In Guneh Barkhord Konim, Page 78; Manhajul Maqal of Astarabadi, Page 343
 aIlm-e-Akhlaq-e-Islami, Volume 1, Page 435; Jamea al-Saaadat, Volume 1, Page 357
 Shanidani-ha-e-Tarikh, Page 373; Mahajjatul Baiza, Volume 6, Page 239
 Hikayat-ha-e-Gulistan, Page 43
 Namunah-e-Maaarif, Volume 2, Page 676; Layaliul Akhbar, Page 197