Have sex with the same wife every four nights

THE WIFE'S RIGHT TO INTERCOURSE

m5.2 (Imam Ghazali:) One should make love to one's wife every four nights, as is fairest, since the number of wives one may have is four, and one may wait this long to do so, though one should make love to her more or less than this, according to the amount she needs to remain chaste and free of want for it (N: if one is able), since it is obligatory for a husband to enable her to keep chaste (Ihya' `ulum aldin (y39), 2.46).