Sefer HaBahir 82

1"[The students asked,] ""And why are there seven limbs in a person?""[Rabbi Rachumai answered,] ""As is written, 'In the image of Elohim, He created the person' (Genesis 9:6), and it is written, 'In the image of Elohim, He created them' (Genesis 1:27). In all of h/His limbs and in all of h/His portions."" [They objected,] ""Thus we have said: why six?""*[He responded,] ""to 'wrap light like a robe' (Psalms 104:2). These six are six borders.""They said to him, ""Circumcision and the partner of a person, we think of as one, and the two hands are three. His head and body are five, two thighs are seven. Corresponding to them, their forces in heaven, as is written, 'Also, Elohim created this opposite that' (Kohelet 7:14). And these are days, 'That six days, God created the heavens and the earth' (Exodus 31:17). It does not say 'in six days,' teaching that every single day has its strength."*See above, number 57."