Imam Malik's Muwatta, Chapter: Shortening the Prayer

Yahya related to me from Malik from Sumayy, the mawla of Abu Bakr, that Abu Bakr ibn Abd ar-Rahman used to say, "Someone who goes to the mosque in the morning or the afternoon with no intention of going anywhere else, either to learn good or teach it, is like someone who does jihad in the way of Allah and returns with booty."