Sahih Muslim , Book 8, Hadith 3418 (USC-MSA) ⓘ
In the narration transmitted on the authority of Ibn Bishr there is a mention of two sucklings and Ibn Abu Shaiba has narrated it with a small variation of wording.
وَحَدَّثَنَاهُ أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ، جَمِيعًا عَنْ عَبْدَةَ بْنِ سُلَيْمَانَ، عَنِ ابْنِ أَبِي عَرُوبَةَ، بِهَذَا الإِسْنَادِ أَمَّا إِسْحَاقُ فَقَالَ كَرِوَايَةِ ابْنِ بِشْرٍ " أَوِ الرَّضْعَتَانِ أَوِ الْمَصَّتَانِ " . وَأَمَّا ابْنُ أَبِي شَيْبَةَ فَقَالَ " وَالرَّضْعَتَانِ وَالْمَصَّتَانِ " .
also referenced under: Book 17, Hadith 27 (In-Book) & Hadith 1451 (Reference)