7718. 'For three days' means a complete state, as just above in 7715.

The number eight represents something that is complete within itself in every respect. Two reasons are offered for this. First, eight is the product of two and four, and two and four both relate to conjunction, or things coming together to form units. Such conjunction leads to completeness, so the product of two and four means completeness. The second reason given is that the eighth day is the start of the second week, and as the first day of that week, it contains within it all that that week represents.