13:5 keep this service. The passover observance was to be kept by the Israelites each year in remembrance and appreciation for what God had done for Israel. As such it became in itself a strong testimony to the Mosaic authorship of the Pentateuch, as well as the deliverance from Egypt. That is, if some group of priests, many centuries later, had invented the whole scenario and then tried to foist it off on the people as having come from Moses, then the fact that no such passover service had been previously practiced by their ancestors, would have immediately revealed the fraud.