Abd al-Rahman bin Abi Layla (may Allah have mercy on him) said: Some people of the Ansar travelled and passed by an Arab tribe. They asked them for hospitality, but they refused. So they seized them and caused them harm. The Bedouins came to Sayyiduna Umar (may Allah be pleased with him), and the Ansar became afraid. Sayyiduna Umar (may Allah be pleased with him) intended to punish them and said: You withhold from travellers the milk that Allah produces in the udders of camels and goats by night and by day! Yet the traveller has more right to the water than the one who resides at it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19669