Sa'id bin al-Musayyib (may Allah have mercy on him) said: When Sayyiduna Umar (may Allah be pleased with him) intended to enlarge the Prophet's Mosque, the house of Sayyiduna al-Abbas (may Allah be pleased with him) fell within that extension. Then he related the story of the spout.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلح / 11364