The word(s) "relation" appears 18 time(s) in 15 verse(s) in Quran in Mohsin Khan translation.

(11) O you who believe! Approach not As-Salat (the prayer) when you are in a drunken state until you know (the meaning) of what you utter, nor when you are in a state of Janaba ,(i.e. in a state of sexual impurity and have not yet taken a bath) except when travelling on the road (without enough water, or just passing through a mosque), till you wash your whole body. And if you are ill, or on a journey, or one of you comes after answering the call of nature, or you have been in contact with women (by sexual relations) and you find no water, perform Tayammum with clean earth and rub therewith your faces and hands (Tayammum) . Truly, Allah is Ever Oft-Pardoning, Oft-Forgiving.

(12) And truly you have come unto Us alone (without wealth, companions or anything else) as We created you the first time. You have left behind you all that which We had bestowed on you. We see not with you your intercessors whom you claimed to be partners with Allah. Now all relations between you and them have been cut off, and all that you used to claim has vanished from you.

(13) It is He Who has created you from a single person (Adam), and (then) He has created from him his wife [Hawwa' (Eve)], in order that he might enjoy the pleasure of living with her. When he (a polytheist from Adam's offspring - as stated by Ibn Kathir in his Tafsir) had sexual relation with her (the polytheist's wife), she became pregnant and she carried it about lightly. Then when it became heavy, they both invoked Allah, their Lord (saying): "If You give us a Salih (good in every aspect) child, we shall indeed be among the grateful."

(14) The adulterer-fornicator marries not but an adulteress-fornicatress or a Mushrikah, and the adulteress-fornicatress none marries her except an adulterer-fornicator or a Muskrik [and that means that the man who agrees to marry (have a sexual relation with) a Mushrikah (female polytheist, pagan or idolatress) or a prostitute, then surely he is either an adulterer-fornicator, or a Mushrik (polytheist, pagan or idolater). And the woman who agrees to marry (have a sexual relation with) a Mushrik (polytheist, pagan or idolater) or an adulterer-fornicator, then she is either a prostitute or a Mushrikah (female polytheist, pagan, or idolatress)]. Such a thing is forbidden to the believers (of Islamic Monotheism).

(15) The Prophet is closer to the believers than their ownselves, and his wives are their (believers') mothers (as regards respect and marriage). And blood relations among each other have closer personal ties in the Decree of Allah (regarding inheritance) than (the brotherhood of) the believers and the Muhajirun (emigrants from Makkah), except that you do kindness to those brothers (when the Prophet صلى الله عليه وسلم joined them in brotherhood ties). This has been written in the (Allah's Book of Divine) Decrees - (Al-Lauh Al-Mahfuz)."