Text

And to the sons of the concubines, that Abraham has, Abraham gave gifts; and he sent them away from upon Isaac, his son, in his being yet alive, towards the east, to eastern land.

Rashi

The concubines

It is written defective, for there was only one concubine; she is Hagar, she is Keturah. Wives are with a ketubah, concubines are without a ketubah, as we say (in Sanhedrin page 21) concerning the wives and concubines of David.

Abraham gave gifts

Our rabbis explained: He handed them a name of defilement (ibid. 91). Another thing: What was given to him because of Sarah and the other gifts which they gave him – all of it he gave to them for he did not want to have pleasure from them.

Ibn Ezra

Gifts

He gave them money.

Towards the east

Its meaning is: To eastern land. And so: ...

Ramban

And to the sons of the concubines, that Abraham has

According to the simple meaning: Because it was said to him: (Genesis 21:12) ...