Mukhtasar Muslim

It is narrated from Sayyiduna Muhammad bin Abi Bakr Thaqafi (may Allah be pleased with him) that he asked Sayyiduna Anas bin Malik (may Allah be pleased with him) while both of them were going from Mina to Arafat: "What would you people do on this day with the Noble Prophet (peace and blessings be upon him)?" Sayyiduna Anas (may Allah be pleased with him) said: "If any of us said 'La ilaha illallah', no one would stop him, and if any of us said 'Allahu Akbar', no one would stop him either."