Bede : And when seven days had passed, the waters of the flood inundated the earth. The seventh day signifies the Sabbath, that is, the rest of future life. Therefore, since the flood signifies the water of baptism, aptly after seven days from when the ark was made it came, because we are baptized in the hope of perpetual rest. However, since the waves of temptations are represented by the waters of the flood, it is also fitting that they come after seven days, because for the sake of faith in the hope of future goods, the just suffer persecution from those who prefer earthly goods to heavenly ones, and the temporal to the everlasting. But indeed, since the flood is compared to the coming of the final judgment, it also fittingly inundates the earth after seven days, because then all the elect who have borne the gentle yoke of Christ and the light burden find rest for their souls. — Commentary on Genesis (Hexaemeron)