One suckling or two do not make (marriage) unlawful.  

قَالَ رَسُولُ اللَّهِ ﷺ وَقَالَ سُوَيْدٌ وَزُهَيْرٌ إِنَّ النَّبِيَّ ﷺ قَالَ لاَ تُحَرِّمُ الْمَصَّةُ وَالْمَصَّتَانِ  

A bedouin came to Allah's Apostle ﷺ when he was in my house and said: Allah's Apostle, I have had a wife and I married another besides her, and my first wife claimed that she had suckled once or twice my newly married wife, thereupon Allah's Apostle ﷺ said: One suckling or two do not make the (marriage) unlawful.  

دَخَلَ أَعْرَابِيٌّ عَلَى نَبِيِّ اللَّهِ ﷺ وَهُوَ فِي بَيْتِي فَقَالَ يَا نَبِيَّ اللَّهِ إِنِّي كَانَتْ لِي امْرَأَةٌ فَتَزَوَّجْتُ عَلَيْهَا أُخْرَى فَزَعَمَتِ امْرَأَتِي الأُولَى أَنَّهَا أَرْضَعَتِ امْرَأَتِي الْحُدْثَى رَضْعَةً أَوْ رَضْعَتَيْنِ فَقَالَ نَبِيُّ اللَّهِ ﷺ لاَ تُحَرِّمُ الإِمْلاَجَةُ وَالإِمْلاَجَتَانِ قَالَ عَمْرٌو فِي رِوَايَتِهِ عَنْ عَبْدِ اللَّهِ بْنِ الْحَارِثِ بْنِ نَوْفَلٍ  

Allah's Apostle, does one suckling make the (marriage) unlawful? He said: No.  

يَا نَبِيَّ اللَّهِ هَلْ تُحَرِّمُ الرَّضْعَةُ الْوَاحِدَةُ قَالَ لاَ  

Being suckled once or twice, or one suckling or two, do not make marriage unlawful.  

أَنَّ نَبِيَّ اللَّهِ ﷺ قَالَ لاَ تُحَرِّمُ الرَّضْعَةُ أَوِ الرَّضْعَتَانِ أَوِ الْمَصَّةُ أَوِ الْمَصَّتَانِ  

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.  

وَالرَّضْعَتَانِ وَالْمَصَّتَانِ  

One or two sucklings do not make (the marriage) unlawful.  

عَنِ النَّبِيِّ ﷺ قَالَ لاَ تُحَرِّمُ الإِمْلاَجَةُ وَالإِمْلاَجَتَانِ  

Does one suckling make (the marriage) unlawful? He said: No.  

عَنْ أُمِّ الْفَضْلِ سَأَلَ رَجُلٌ النَّبِيَّ ﷺ أَتُحَرِّمُ الْمَصَّةُ فَقَالَ لاَ