Allah, the Wise, has said:
أََلسَّارِقُ وَ السَّارِقَةُ فَاقْطَعُوا أََيْدِيَهُمَا
"And (as for) the man who steals and the woman who steals, cut off their hands." 
Imam Sadiq (as):
إِذَا سَرَقَ السَّارِقُ قُطِعَتْ يَدُهُ وَ غُرِمَ ماَ أَخَذَ
"When a thief commits a theft, his hands are cut and he is made to indemnify what he has taken." 
Denying the wife her dower, not repaying one's debts, not paying one's obligatory zakat and so on, are also examples of theft, but the meaning that immediately comes to mind upon hearing of theft, is 'taking into possession the property and wealth of others, secretly and deceptively' . This is the meaning which is actually intended here.
If there were to be no security (in the society), the people would be unable to sleep in peace for fear of thieves. It is for the purpose of establishing and maintaining security that Islam has ordered a thief's fingers to be severed; even if the act happens to be committed by a child, he has to be castigated in some manner, so that he desists from committing this evil act in the future.
It is due to the non-implementation of this Qur'anic ruling that an increasing number of thieves are found even in Islamic societies these days.
1 – The Imam and the Thief's Confession
A person approached Imam Ali (as) and confessed that he had committed a theft.
"Are you able to recite something from the Noble Qur'an?" Imam (as) asked him.
"Yes, I know the chapter al-Baqarah," replied the man.
The Imam (as) said, "I forgive you because of the chapter al-Baqarah." Ashaath Ibn Qais, who happened to witness this, asked the Imam (as) whether he could repeal a punishment that had been stipulated by Allah.
"What do you know? If a person confesses to his crime, an Imam has the authority to either punish him or pardon him, but if two persons testify to a person's crime, it is not permissible to annul the punishment (and pardon him)," the Imam (as) retorted.)
2 – The Bedouin's Camel
Sheikh Tawoos al-Haramain narrates: "I had been standing near Masjid al-Haram in Makkah when I witnessed a Bedouin advancing on his camel. When he reached the mosque, he dismounted, made his camel sit down, tied its two knees and then, raising his head towards the sky, implored: "O' Lord! I entrust unto You this camel and the load that lies upon it." Then he entered Masjid al-Haram. When he had circumambulated the Ka'bah and offered his prayers, he came out of the mosque and found his camel missing. He looked up towards the sky.
"It has been said in the holy Shari'ah that property should be sought from one, unto whom it has been placed as trust. I had entrusted my camel unto You, so return my camel to me," he said.
Hardly had he uttered these words when I observed that someone emerged from behind the mountain of Abu Qubais, with the rein of a camel in the left hand and the right hand severed and suspended from his neck. He came close to the Bedouin.
"O' Youth! Take hold of your camel," he said.
"Who are you and how did you land up in this state?" asked the Bedouin.
"I was impoverished and needy and hence stole your camel," said the stranger. "I went behind the mountain of Abu Qubais when I suddenly noticed a rider coming towards me. As he came closer to me, he shouted out: Bring your hand forward. When I had extended my hand, he severed it with a stroke of his sword and, hanging it on my neck, said to me: Return this camel to its owner immediately." 
3 – Buhul and the Thief
Whenever Buhul happened to have money in excess of his expenses, he used to save it by concealing it in one corner of a ruined and broken down house; this continued till the amount eventually reached a figure of three hundred dirhams.
The next occasion when he had saved another ten dirhams and had gone to the place to add it to his concealed savings, a trader who lived in the neighbourhood, found out about the hideout. As soon as Buhul had left the hiding place, the neighbour dug up the money that was concealed beneath the ground.
The next time when Bulool came to the place, he found his money missing and immediately realized that it was the work of the trader. He decided to approach the trader.
"I wish to trouble you by telling you about my secret," Buhul said to the trader. "I have placed my money in different places." Then he began enumerating the places till the entire figure reached three thousand dirhams. "The place where I have placed three hundred and ten dirhams is the safest of them all. I now wish to transfer all my money to this place in the ruined house." Saying this, he bid the trader goodbye and left.
The trader decided to return the three hundred and ten dirhams to the place from where he had stolen the money with the intention that when Buhul placed all his money there, he would steal the increased amount. Some days later, Buhul returned to the ruins and found the three hundred and ten dirhams in its original location. Taking out the money, he defecated there and covered it with earth.
Immediately after Buhul had left, the trader rushed towards the spot and, removing the earth, sought to collect the entire money, only to find his hand dirtied by the excrement. He thus comprehended Buhul's deception. A few days later Buhul visited him.
"I want you to compute some figures associated with my money," said Buhul. "How much does eighty dirhams added to fifty dirhams added to one hundred dirhams, and this sum added to the dirty odour that emanates from your hands, sum up to?"
Saying this, he took to his heels. The trader rushed after him in hot pursuit, but failed to catch him.
4 – The Qur'an-Reciting Blind Thief
'Allam Ibn Al-Thaman says: "I was employed by a trader in Basrah when one day, I had to undertake a journey to aUbullah. I put five hundred dirhams in a bag and set out for the journey. I reached the banks of the river Tigris where I hired a boat. As I was passing by the region named Mismar, I noticed a blind person sitting by the riverbank, reciting the Qur'an. In a very sad voice, he called out: "O' Seaman! Take me in the boat for I fear that the animals might kill me at night." Initially the boatman refused but when I rebuked him, he consented. The blind man sat in the boat and continually recited the Qur'an from memory till we came near aUbullah, whereupon he stopped his recitation and began to disembark from the boat.
All of a sudden, I realized that the trader's money, which had been given to me in trust, was missing. Both the boatman and the blind person removed their clothes to prove that they had not taken the money. I thought to myself, "The trader is bound to kill me." Thousands of thoughts whirled in my mind and I began to weep and pray.
As I walked towards aUbullah, a man came up to me and sought to know the reason for my lamentations. I informed him of the theft of the trader's money.
"I shall show you a way (to extricate yourself from this problem)," he said. "Purchase some good food, go to the prison and plead to the prison warden to let you in. Inside the prison, go to Abu Bakr Naqqash and give him the food. He will inquire about your problem, and when he does so, narrate the entire story to him."
I followed his instructions and when I had narrated my problem to Abu Bakr Naqqash, he said: "Now proceed towards the tribe of Bani Hilal and go to a certain house. Open the door and enter the house. There you will notice some handkerchiefs hanging behind the door. Tie one of them to your waist and sit down in a corner. A group of people will enter and engage themselves in consuming intoxicants; you should pick up a bowl too and after calling out, 'For the health of my (maternal) uncle, Abu Bakr Naqqash,' begin drinking from it. Upon hearing my name, they will inquire after my health. Pass this message to them: 'Yesterday, my nephew's money was stolen. Hand it back to him,' and they will hand over the money to you."
I did as instructed and they too, without any protest, handed over the bag of money to me. I requested them to inform me as to how the theft had taken place. After great reluctance, one of them asked me if I recognised him. Looking closely at him, I realized he was the same blind man who had been reciting the Qur'an, while the other person was the boatman.
"One of our associates swims underwater behind the boat," he explained. "When the Qur'an is recited, the traveller becomes so absorbed that he does not notice that we have thrown his money into the water. It is collected by the associate in the water and carried to the shore, to be distributed amongst ourselves when we gather together the next day. Today was the day for the distribution of the money, but since we have received orders from our chief, Abu Bakr Naqqash, we have returned the money to you."
I took possession of the money and thanked Allah for having been delivered from this quandary.
 Noble Qur'an, Suratul Maidah (5), Verse 38
 Tafsirul Mu`in, Page 114
 Qadhawat-ha-e-Amirul Moaminin(as), Page 119 (authored by Tustari
 Rahnama-e-Saaadat, Volume 2, Page 272; Khulasatul Akhbar, Page 526
 Dastan-ha Wa Pand-ha, Volume 2, Page 71; Khazain Naraqi
 Jawamea al-Hikayat, Page 357