"..the word of the Lord came to Abram in a vision: "Fear not, Abram, I am your shield; your reward shall be very great." But Abram said, O Lord God , what will you give me for I continue childless..?"
There is on this site a question concerning magen/benefactor/shield, here I would like to focus on "reward".
After "your reward shall be very great" Abram replies ["But Abram said"] in terms of having an heir. God then replies to Abram with "...your very own son shall be your heir".
"reward" here is linked to Abram's offspring. In Gen 15:18 "offspring" is associated with "land".
Thus in the ESV "reward" maybe seen as related to "heirs" and "land".
However, in Bible Hub about half of the versions quoted agree with the ESV and the others agree with the NKJV "I am your shield, your exceedingly great reward".
Here [NKJV] it is as if God were saying that, yes, Abram we will talk about heirs and land but first remember-I am your exceedingly great reward.
God is no doubt the reward of a devout life but what does the Hebrew say is Abram's reward in this verse?