Musannaf Ibn Abi Shaybah

The narrator says that I asked Hazrat Ata (may Allah have mercy on him) that we entrust merchandise to people, and then on the way we ourselves need it, so what is the ruling for us? Can we take it? He replied: If you reach your destination, will you sell the needed items to the people? I said, why not. He said: Then there is no harm. This is better for the owner of the goods.

Hazrat Hasan (may Allah be pleased with him) was asked about a person who was given some dirhams so that he could buy something with them. He spent those dirhams on his own needs, then returned them and bought the same thing that he was told to buy. He (may Allah be pleased with him) said: As long as he does not hand it over to the owner, he will be held liable.