Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "Whoever drinks water on an empty stomach, his strength is diminished."
Al-Tabarani recorded it in al-Mu'jam al-Awsat, and its chain contains Muhammad bin Makhlad al-Ru'ayni, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطب / 8292