Ahmed bin 'Amr bin al-Sarh أحمد بن عمرو بن السرح أبو الطاهر · Wages (Kitab Al-Ijarah)

Do not go our to meet what is being brought (to market for sale). If anyone does so and buys some of it, the owner of merchandise has a choice (of canceling the deal) when it comes to the market. Abu 'Ali said: I heard Abu Dawud say: Sufyan said: none of you must buy in opposition to one another ; that is he says: I have a better one for ten (dirhams).

The Prophet (ﷺ) said: The similitude of the one who takes back what he gifted is like that of a dog which vomits and then it eats vomit. When a donor seeks to take back (his gift), it should be made known and he informed why he sought to take it back. Then whatever he donated should be returned to him.