Musannaf Ibn Abi Shayba 16:202

Abu Bakr narrated to us, he said: Ibn ‘Uyaynah narrated to us, from Muhammad ibn ‘Ajlan, from Sa‘id ibn Abi Sa‘id, from Abu Hurayrah, who said: When you enter upon your Muslim brother and he feeds you food, then eat and do not ask. If he gives you a drink, then drink and do not ask. If something about it makes you suspicious, then dilute it with water.