Musnad Ahmad 937:32

'Affan narrated to us, Wuhayb narrated to us, Abu Mas'ud al-Jurayri narrated to us, from Abu 'Abd Allah al-Jasri, from 'Abd Allah ibn al-Samit, from Abu Dharr, who said: The Messenger of Allah (peace and blessings of Allah be upon him) was asked: "Which speech is best?" He said: "That which Allah has chosen for His servants: 'Glory be to Allah and by His praise' (Subhan Allah wa bi-hamdihi)."