It is narrated from Sayyidah Umm al-Fadl (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) said: "Sucking once or twice, or being breastfed once or twice, does not establish the prohibition (of marriage)."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21493