Sayyiduna al-Mughirah bin Shu'bah (may Allah be pleased with him) said: the Messenger of Allah (peace and blessings be upon him) said: "The 'anaqah (a small amount of suckling) does not establish the prohibition of fosterage." We asked: What is the 'anaqah? He (peace and blessings be upon him) said: "A woman gives birth and the milk is held back (and collects) in her breast, so she suckles her neighbour's (child) once or twice."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 18089