“It was the seventh day, and all things were accomplished.”

And again:

“And on the seventh morn we leave the stream of Acheron.”

Callimachus the poet also writes:

“It was the seventh morn, and they had all things done.”

And again:

“Among good days is the seventh day, and the seventh race.”

And:

“The seventh is among the prime, and the seventh is perfect.”

And: