Sayyidah Aishah (may Allah be pleased with her) said: The Messenger of Allah (peace and blessings be upon him) and I used to bathe from a single vessel. He (peace and blessings be upon him) would hurry ahead of me and I would hurry ahead of him (peace and blessings be upon him), until I would say: "Leave some for me, leave some for me." This is how she said it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 894