It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "When one of you hears the call (to prayer) while the vessel is in his hand, let him not put it down until he has fulfilled his need from it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8019