This is the account of the fourth direct appearance of Jehovah to Abram and evidently it had direct connection with what had immediately preceded. Abram had passed through two conflicts, the first with kings, the second with the suggestion of enrichment from the treasury of Sodom. In both he had been victorious. Now the divine voice declared, first, "I am thy shield," reminding him of how his victory over the kings had been obtained; while the second word, "I am... thy exceeding great reward" reminded him that he had lost nothing in refusing the reward offered by the king of Sodom.
In response to this word of God Abram's faith moved to a higher level. He was able to speak to God of the temptation to doubt which was in his heart. He was at once answered with the divine promise of an heir and was commanded to look at the stars to find the measure of the issue, "if thou be able to number them." Abram could not, but God could. So was his seed to be. Looking at the stars, he would know there was order where he could not discover it, number where he could not follow it; purpose where he could not trace it. He believed very literally; he built on God and God counted it to him for righteousness.
Jehovah now repeated the promise that he should inherit the land and in response to Abram's request gave him a sign. It was given in connection with sacrifice. In a horror of great darkness Abram received the revelation of trouble that lay ahead of his people and of an issue out of it. This, by the significant vision of a smoking furnace and a lamp. Abram's request for a sign was the request of faith. Therefore it was granted. When unbelief requests a sign, it is refused.