And to the sons of Avraham's concubines, Avraham gave gifts.
Avraham wished to ensure that his entire inheritance reached Yitzchok and Klal Yisroel, with nothing for the other nations that emerged from him. He gave them all gifts, to ensure that they do not complain.
The Ohr Hachaim notes an omission. One child of Avraham’s did not receive anything, will he not return to complain? Yishmael, the oldest son. Yishmael was sent away with a skein of water, and he did not receive anything.
The Ohr Hachaim refers you back to what he wrote in Parshas Vayera. Hagar was a maidservant, and when Avraham married her, she did not lose that status. Yishmael was born a slave and everything that he owned belonged to Yitzchok and his descendants. Giving him a gift would not benefit him, because it all belongs to Yitzchok anyway.
The Ohr Hachaim adds that this may not be visible to us now. We see that Yishmael is a powerful nation, and not enslaved at all. However, this will be overturned. Hashem has a day of judgment in His mind, and then He will show the truth to all, and Yishmael’s enslaved status will be obvious to his owner.
