Genesis 12:8

And there he built an altar unto the Lord who appeared to him, and called on the name of the Lord — Now consider this, As done upon a special occasion when God appeared to him, then and there he built an altar, with an eye to the God that appeared to him: thus he acknowledged with thankfulness God's kindness to him in making him that gracious visit and promise: and thus he testified his confidence in, and dependence upon the word which God had spoken. As his constant practice, whithersoever he removed. As soon as Abram was got to Canaan, though he was but a stranger and sojourner there, yet he set up, and kept up, the worship of God in his family; and wherever he had a tent, God had an altar and that an altar sanctified by prayer.