At the request of the Prophet (SAW) of Islam, Hadrat Ali (AS) went to buy a shirt for him. Hadrat Ali (AS) went to the market and bought a shirt for twelve Dirhams. Hadrat Muhammad (SAW) asked.
"For how many Dirhams did you buy it?"
"For twelve Dirhams."
"I didn't like it, I want a cheaper one. Would the shopkeeper take it back?"
"I don't know, O Messenger (SAW) of Allah."
"Please go and see if he agrees to take it back."
Hadrat Ali (AS) took the shirt to the shopkeeper and said to him: "The Messenger (SAW) of Allah wants a cheaper shirt; would you agree to take it back and give back the money?"
The shopkeeper agreed to do so and he gave the money back to Hadrat Ali (AS). Hadrat Ali (AS) took the money to the Prophet (SAW). After this, Hadrat Muhammad (SAW) and Hadrat Ali (AS) went to the market together. While on the way, the Prophet (SAW) saw a slave-girl, who was crying. He went to her and asked:
"Why are you crying?"
"My master gave me four Dirhams to buy things from the market. I don't know where that money got lost. Now, I don't have the courage to go home.
Out of twelve Dirhams, Hadrat Muhammad (SAW) gave four Dirhams to the slave-girl and said: "Buy whatever you had to buy and go back home." Prophet (SAW), himself, went to the market and after buying a shirt for four Dirhams, he put it on.
While coming back from the market, he saw an undressed man. He quickly took off his shirt and gave it to him. He again went to the shop and bought another shirt for four Dirhams. He put it on. On his way, he again saw the same slave-girl, who was sitting scared and troubled. He asked:
"Why didn't you go home?"
"O Messenger (SAW) of Allah, it's too late for me and I am scared that they might beat me and ask as to why I took so long."
"Tell me the address of your house and come with me, so that I might request that no one should say anything to you." Hadrat Muhammad (SAW) took the slave-girl with him. As soon as they reached near the house, the girl said: "This is the house." With a loud voice, the Messenger (SAW) of Allah said:
"My salaam to you, the inhabitants of this house."
He didn't get any reply; so he again said, salaam. But still he got no reply. He said salaam for the third time and then everyone replied saying: "Assalamu Alayk, O Messenger of Allah (SAW)."
"Why didn't you people respond me for the first time? Did you not hear my voice?"
"Yes! After hearing your voice for the first time itself, we came to know that it was you."
"Then what was the reason for the delay in response?"
"O Messenger (SAW) of Allah, we loved to hear your voice (salaam) again and again. Your salaam is virtuous, peace and blessing for us."
"Your slave-girl has taken long in coming back. Hence, I have come to request that you don't punish her."
"O the Messenger (SAW) of Allah! By the blessing of your gracious coming over to our place, we have set this girl free." The Prophet (SAW) said: "Thanks a million to Allah. How blessed these twelve Dirhams were; with which two undressed persons got dressed as well as a slave-girl got free."
Read another similar story called as "The Glorious Necklace" Anecdotes of Pious People