Sahih Muslim 2172
Sahih Muslim · Book 39: The Book of Greetings · The Prohibition Of Being Alone With A Non-Mahram Woman Or Entering Upon Her
Ibn Wahb reported:
وَحَدَّثَنِي أَبُو الطَّاهِرِ ، أَخْبَرَنَا ابْنُ وَهْبٍ ، قَالَ سَمِعْتُ اللَّيْثَ بْنَ سَعْدٍ ، يَقُولُ الْحَمْوُ أَخُ الزَّوْجِ وَمَا أَشْبَهَهُ مِنْ أَقَارِبِ الزَّوْجِ ابْنُ الْعَمِّ وَنَحْوُهُ .
I heard Laith b. Said as saying: Al-Hamv means the brother of husband or like it from amongst the relatives of the husband, for example, cousin, etc.