I shall not be pleased unless you call Allah's Messenger (ﷺ) as witness to what you confer as a gift on your son. (Nu'man said): So father took hold of my hand and I was at that time a boy, and came to Allah's Messenger (ﷺ). and said: Allah's Messenger, the mother of this son (of mine), daughter of Rawaha wishes that I should call you witness to what I confer as gift to her son. Allah's Messenger (may pease be upon him) said: Bashir, have you any other son besides this (son of yours)? He said: Yes. He (the Holy Prophet) said: Have you given gifts to all of them like this? He said: No. Thereupon he (the Holy Prophet) said: Then call me not as witness, for I cannot be witness to an injustice.
Sahih Muslim Book 24, Hadith 20
← Previous Hadith My father donated to me some of his property. My mother Amra bint Rawaha said: I shall not be pleased (with this act) until you make Allah's Messenger (ﷺ) a witness to it. My father went to Allah's Apostle (ﷺ) in order to make him the witness of the donation given to me. Allah's Messenger (ﷺ) said to him: Have you done the same with every son of yours? He said: No. Thereupon he (the Holy Prophet) said: Fear Allah, and observe equity in case of your children. My father returned and got back the gift.

Sahih Muslim Book 24, Hadith 19 Next Hadith → Have you, besides him, other sons? He said: Yes. Thereupon he (the Holy Prophet) said: Have you given gifts to all of them like this (as you have given to Nu'man)? He said: No. Thereupon he (the Holy Prophet) said: I cannot bear witness to an injustice.

Sahih Muslim Book 24, Hadith 21