Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) said: "Tawaf around the House is prayer, except that speaking has been permitted in it; so whoever is able to speak nothing but good, let him do so."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9292