No mention of works--God just blessing Abraham
Now the LORD said unto Abram: 'Get thee out of thy country, and from thy kindred, and from thy father's house, unto the land that I will show thee. And I will make of thee a great nation, and I will bless thee, and make thy name great; and be thou a blessing. And I will bless them that bless thee, and him that curseth thee will I curse; and in thee shall all the families of the earth be blessed.'--Genesis 12:1-3
And the LORD appeared unto Abram, and said: 'Unto thy seed will I give this land'; and he builded there an altar unto the LORD, who appeared unto him.--Genesis 12:7
And the LORD said unto Abram, after that Lot was separated from him: 'Lift up now thine eyes, and look from the place where thou art, northward and southward and eastward and westward; for all the land which thou seest, to thee will I give it, and to thy seed for ever. And I will make thy seed as the dust of the earth; so that if a man can number the dust of the earth, then shall thy seed also be numbered. Arise, walk through the land in the length of it and in the breadth of it; for unto thee will I give it.'--Genesis 13:14-17
And He brought him forth abroad, and said: 'Look now toward heaven, and count the stars, if thou be able to count them'; and He said unto him: 'So shall thy seed be.' And he believed in the LORD; and He counted it to him for righteousness.--Genesis 15:5-6
In that day the LORD made a covenant with Abram, saying: 'Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates;--Genesis 15:18In these prior verses Abraham did not do much besides move where God said to and believe. However, after Genesis 22 when Abraham was willing to sacrifice Isaac because of God's request, God now cites His previous promises as being done BECAUSE of Abraham's works and obedience, even using the same language about the stars and sand.
By Myself have I sworn, saith the LORD, because thou hast done this thing, and hast not withheld thy son, thine only son, that in blessing I will bless thee, and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the seashore; and thy seed shall possess the gate of his enemies; and in thy seed shall all the nations of the earth be blessed; because thou hast hearkened to My voice.'--Genesis 22:16-18
And the LORD appeared unto him, and said: 'Go not down unto Egypt; dwell in the land which I shall tell thee of. Sojourn in this land, and I will be with thee, and will bless thee; for unto thee, and unto thy seed, I will give all these lands, and I will establish the oath which I swore unto Abraham thy father; and I will multiply thy seed as the stars of heaven, and will give unto thy seed all these lands; and by thy seed shall all the nations of the earth bless themselves; because that Abraham hearkened to My voice, and kept My charge, My commandments, My statutes, and My laws.'--Genesis 26:2-5Genesis 26 explicitly refers to Abraham's blessing because of his commandment/statute/law keeping.
Abraham also tells others about the Covenant with God in Genesis 24, not mentioning his obedience:
The LORD, the God of heaven, who took me from my father's house, and from the land of my nativity, and who spoke unto me, and who swore unto me, saying: Unto thy seed will I give this land; He will send His angel before thee, and thou shalt take a wife for my son from thence.--Genesis 24:7Why doesn't Abraham mention his works this time after Genesis 22? Because of humility, and it was all possible BECAUSE of what God did.
We see in Abraham a man that believed God and was accredited with righteousness, but the very thing he believed was partly accomplished because of Abraham's obedience to God. God made these promises because God knew in advance that Abraham WOULD be obedient and keep His Commandments once he believed!