And it was so, when the days of their feasting were gone about, that Job sent and sanctified them, and rose up early in the morning, and offered burnt offerings according to the number of them all: for Job said, It may be that my sons have sinned, and cursed God in their hearts. Thus did Job continually.
After their celebration ended, Job sent for them, purified them, and early in the morning, offered sacrifices based on their number. He did this because he thought his sons might have sinned and cursed God in their hearts. This is what Job consistently did.