Genesis 35:7
And he built there an altar, and called the place El-beth-el: because there God appeared unto him, when he fled from the face of his brother. And he built there an altar, and called the place El-beth-el: because there God appeared unto him, when he fled from the face of his brother.
The altar at Bethel was built as a memorial to God's earlier appearance to Jacob when he was fleeing for his life from his brother. God accepted Jacob's effort to remove wrongdoing from his household, and then appeared to him at Bethel, blessed him, and renewed the promise previously made to him. At the place where God spoke to him, Jacob set up a stone pillar in addition to the altar. The place recalled God's promises of mercy and Jacob's vow that the Lord would be his God. There Jacob remembered that God had answered him in distress and had stayed with him on his journey.