Then the Lord appeared to Abram and said, “To your offspring I will give this land.” So he built there an altar to the Lord, who had appeared to him. From there he moved to the hill country on the east of Bethel and pitched his tent, with Bethel on the west and Ai on the east. And there he built an altar to the Lord and called upon the name of the Lord.
Now Abram was very rich in livestock, in silver, and in gold. 3 And he journeyed on from the Negeb as far as Bethel to the place where his tent had been at the beginning, between Bethel and Ai, 4 to the place where he had made an altar at the first. And there Abram called upon the name of the Lord.
To “call on the name of the Lord” meant to worship God. This is made clearer, for example, in the Common English Bible which translates the phrase: “worshipped in the Lord’s name.”
Abram built several altars in his travels, and at each one he worshipped the Lord.