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
Ata (may Allah have mercy on him) said: I performed tawaf behind Ibn Umar and Ibn Abbas (may Allah be pleased with them), and I did not find either of them speaking until he had finished.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9295
Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) said: Whoever performs tawaf of this House seven times, speaking nothing in it except the takbir and the tahlil, it is equal to freeing a slave.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9296