Sayyiduna Dirar bin al-Azwar (may Allah be pleased with him) narrates: My family sent me with a milch she-camel to the Messenger of Allah (peace and blessings be upon him), which they had given to him (peace and blessings be upon him) as a gift, and he (peace and blessings be upon him) said to me: "Milk her, and leave some milk rather than squeezing it out completely." And he (peace and blessings be upon him) prayed for me.
Hadith Referenceالمعجم الكبير للطبراني / باب الضاد / 8098