Maliks Muwatta Book 014, Hadith Number 006.

Section : The Prohibition against Spitting towards the Qibla.

Yahya related to me from Malik from Abdullah ibn Dinar that Abdullah ibn Umar said, "On one occasion when the people were praying subhat Quba a man came to them and said, 'A piece of Qur'an was sent down to the Messenger of Allah, may Allah bless him and grant him peace, last night, and he was ordered to face the Kaba, so face it.' They had been facing ash-Sham, so they turned round and faced the Kaba.'"