Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Tawaf of the House is prayer, but Allah has made speaking lawful in it; so whoever speaks, let him say nothing but good."
Ata and Layth bin Abi Sulaym narrated it as marfu' (attributed to the Prophet), while Abdullah bin Tawus and Ibrahim bin Maysarah narrated it as mawquf (stopping at Ibn Abbas) in the authentic narration.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9304