islam is ambiguous - well possibly
the arabic word is zina. it ( appears ) to occur 14 times in the Quran
https://quran.com/search?q=adultery
different words for the adulterer and adulteress. All 14 are pretty against it. Slaves dont count so kissing a slave is OK - that may be what he meant.
and the words adultery and lawful never seem to occur together.
They have a body of law ( qanun(*) that is based firmly on the Quran and sayings ( hadith ) of those who came after of varying importance. This explains the law - four male witnesses for adultery spring to mind. No man in his right mind will bring four of his frenz to witness his wife in flagrante with a sixth ( four+ husband+ lover)
in an automatic translator I did put in - statutes of the country
and got out - - قوانين البلاد - quawaneen al bilad - quawaneen take it from me is plural of qanun - so he may be referring to moroccan law.
then I lost interest - they wouldnt cheerfully stone people if it were lawful.
(*) yes qanun is a loan word from Latin canon - as in canon of law or canon law. - others are sejel from sigilla ( clay seal ) and qalm from calamus scriptorius - writing reed - oh qatt and cat