Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) was asked what is lawful for a person from his brother's property. He (peace and blessings be upon him) said: "When he is hungry or thirsty, he may eat and drink his fill."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19660