All righteous human actions, including sexual relations within the bonds of marriage, are considered to be a form of worship of Allah.  There is evidence that the Prophet taught his followers that sexual relations between a husband and wife carried spiritual rewards-because sex sanctioned by law prevented the unlawful satisfaction of carnal desire.

fromThe Complete Idiot's Guide to the Koran by Shaykh Muhammad Sarwar and Brandon Toropov

So, by comparison to St Paul's rather grudging allowance of marital sex for those not strong enough to do without, a ringing endorsement.