Why might Abram have felt God had forgotten His promise?
Abram had waited thirty-six years after the Genesis 12 promise that he would have a son and from him a special race. No child had been born, Sarai showed no signs of being able to conceive, and the long delay made it seem God had forgotten His promise.
Les teaches that Abram was still called Abram at this point and had already been waiting thirty-six years for the promise of Genesis 12 to be fulfilled. That promise was that he would have a son, and out of that son would come a special race or nation of people. After thirty-six years, there was still no child, and Sarai had no signs whatsoever of ever being able to have a child. Les explains that this was a long time by any standard, so Abram might naturally feel that God had forgotten and was never giving him the promise.
More Questions
How long had Abram been waiting for God's promise of a son to be fulfilled?
By the time of the events in Genesis 16, Abram has already been waiting 36 years for the promise of Genesis 12 to be fulfilled.
When was the Law given in relation to God's promises to Abram?
The giving of the Law came after Abram came out and was given all the promises in Genesis chapters 12, 15, and 17.