Moses
Genesis 15:3BSB·traditional attribution

Abram continued, “Behold, You have given me no offspring, so a servant in my household will be my heir.”

Matthew Henry Presbyterian @wholebiblehenry

We have here the assurance given to Abram of a numerous offspring which should descend from him, in which observe, I. Abram's repeated complaint, Gen 15:2, Gen 15:3. This was that which gave occasion to this promise. The great affliction that sat heavy upon Abram was the want of a child; and the complaint of this he here pours out before the Lord, and shows...

Commenting on Genesis 15:2-6

John Gill Reformed Baptist @doctorgill

And Abram said, behold, to me thou hast given no seed,.... He had bestowed many temporal blessings on him, as well as spiritual ones, having given himself in covenant, and all things in it, but he had not given him a child: and lo, one born in my house is mine heir; meaning either Eliezer or his son, whom he had made his heir, or...

Jamieson-Fausset-Brown Reformed @jfbcommentary

Eliezer of Damascus . . . one born in my house is mine heir--According to the usage of nomadic tribes, his chief confidential servant, would be heir to his possessions and honors. But this man could have become his son only by adoption; and how sadly would that have come short of the parental hopes he had been encouraged to entertain!