Musnad Ahmad 1018:12

Waki’ narrated to us, from Yunus bin Abi Ishaq, who said: I heard Jarri bin Kulayb al-Nahdi, from a man from Banu Sulaym, who said: The Messenger of Allah (may Allah bless him and grant him peace) counted them on my hand, or on his hand: "Tasbih (saying SubhanAllah) is half of the Scale, and 'Alhamdulillah' (praise be to Allah) fills it, and 'Allahu Akbar' (Allah is the Greatest) fills what is between the heaven and the earth. Fasting is half of patience, and purification is half of faith."