Since Sarah continued to be barren, it appeared that Eliezer the faithful house steward from Damascus would receive Abraham’s inheritance. Nevertheless, Jehovah again reassured Abraham that his own offspring would become uncountable, as the stars of heaven, and so Abraham “put faith in Jehovah; and he proceeded to count it to him as righteousness,” even though this occurred years before Abraham was circumcised. (Ge 15:1-6; Ro 4:9, 10)

The supreme test of Abraham’s faith came about 20 years later. According to Jewish tradition, Isaac was now 25 years old. (Jewish Antiquities, by F. Josephus, I, 227 [xiii, 2]) In obedience to Jehovah’s instructions Abraham took Isaac and traveled N from Beer-sheba at the Negeb to Mount Moriah, situated directly N of Salem. There he built an altar and prepared to offer up Isaac, the promised seed, as a burnt sacrifice. And indeed Abraham “as good as offered up Isaac,” for “he reckoned that God was able to raise him up even from the dead.” Only at the last moment did Jehovah intervene and provide a ram as a substitute for Isaac on the sacrificial altar. It was, therefore, this implicit faith backed up by complete obedience that moved Jehovah to reinforce his covenant with Abraham with a sworn oath, a special legal guarantee.​—Ge 22:1-18; Heb 6:13-18; 11:17-19.

Abraham, like Abel, Enoch, and Noah, was a man of faith. (Heb 11:4-9) But the first occurrence of the expression “put faith in Jehovah” is in reference to Abraham.​—Ge 15:6.

Indeed, this man of unusual faith walked with God, received communications from him by means of visions and dreams, and entertained his angelic messengers. (Ge 12:1-3, 7; 15:1-8, 12-21; 18:1-15; 22:11, 12, 15-18) He was well acquainted with the name of God even though Jehovah had not at that time revealed the full significance of His name. (Ex 6:2, 3) Time after time Abraham built altars and offered up sacrifices in the name of and to the praise and glory of his God Jehovah.​—Ge 12:8; 13:4, 18; 21:33; 24:40; 48:15.

As patriarchal head, Abraham allowed no idolatry or ungodliness in his household but constantly taught all his sons and servants to “keep Jehovah’s way to do righteousness and judgment.” (Ge 18:19) Every male member of Abraham’s household was bound by Jehovah’s law to submit to circumcision. The Egyptian slave girl Hagar called on Jehovah’s name in prayer. And Abraham’s oldest servant in a very heart-touching prayer to Jehovah demonstrated his own faith in Abraham’s God. Isaac too, in his early manhood, proved his faith and his obedience to Jehovah by allowing himself to be bound hand and foot and placed atop the altar for sacrifice.​—Ge 17:10-14, 23-27; 16:13; 24:2-56.