Gregory the Great

He shall deliver thee in six troubles, yea, in seven there shall no evil touch thee.

For what is denoted by the number 'six,' which is followed by 'the seventh,' saving the labour and course of the present life? For God, finishing all things on the sixth day, created man, and God rested on the seventh day; and this same seventh day is without an evening, for there is no longer any end to close the rest that followeth. When all things, then, are completed, the rest followeth, in that after the good works of the present life, the recompense of eternal rest follows. Therefore 'in six troubles the Lord delivers us,' that 'no evil may touch us in the seventh,' in that by the training of His fatherly pity, He exercises us with the labours of the present life, but at the coming of the Judge, He hides us from the scourge, that He may then bring us out the more sure for His salvation, in proportion as we are now scored the more cruelly with scourges.