He observed the daily requirements for sacrifices that Moses had specified for Sabbaths, new moon festivals, and the three annual celebrations--the Feast of Unleavened Bread, the Feast of Weeks, and the Feast of Temporary Shelters.
Genesis 26:8
After Isaac had been there a long time, Abimelech king of the Philistines happened to look out a window and observed Isaac caressing his wife Rebekah.
Genesis 31:12
Then he said, 'Observe that all the male goats mating with the flock are streaked, speckled, or spotted, for I have observed all that Laban has done to you.
Genesis 39:3
His master observed that the LORD was with him and that the LORD made everything he was doing successful.
Genesis 46:1
So Israel began his journey, taking with him all that he had. When he came to Beer Sheba he offered sacrifices to the God of his father Isaac.
Genesis 50:10
When they came to the threshing floor of Atad on the other side of the Jordan, they mourned there with very great and bitter sorrow. There Joseph observed a seven day period of mourning for his father.