Hukaymah bint Umaymah bint Ruqayqah (may Allah be pleased with her) narrates from her mother that the Prophet (peace and blessings be upon him) had a wooden cup that was kept under his (peace and blessings be upon him) bed, and at night he (peace and blessings be upon him) would urinate in it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 481