Nu'man b. Bashir reported that his mother bint Rawaha asked his (Nu'man's) father about donating some gifts from his property to his son. He deferred the matter by one year, and then set forth to do that. She (Nu'man's mother) said: 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 (ﷺ) , 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 Prophet) said: Have you given gifts to all of them like this? He said: No. Thereupon he (the Prophet) said: Then call me not as witness, for I cannot be witness to an injustice.
