He who sings prays twice.
Widely attributed to St. Augustine, even in the Catechism of the Catholic Church, which even gives a citation. I remember it as a poster on the wall of the choir rehearsal room in the church where I grew up. Unfortunately, as Fr. John Zuhlsdorf documents in this blog post, the saying doesn’t appear in Augustine where the CCC says it does. (I have seen Fr. Z cited as saying that St. Augustine said, “I can still say with the oft quoted citation: ‘He who sings well prays twice’, so long as it is from love.” This is Fr. Z’s own phrase, waxing poetic. St. Augustine didn’t say it, and Fr. Z didn’t claim he did.) Wikiquote gives the same citation as the CCC.
The complete works of Augustine are searchable online. I searched for qui canit bis orat, and, for good measure, qui bene cantat bis orat. It’s not there under either phrasing. So I’m about as confident as can be that it’s not from St. Augustine. (I am not going to get into edit wars on Wikiquote.)
Which raises the question … where did it come from and how did it get attached to St. Augustine? I tried Google Books with custom date ranges. I can’t find it at all before 1940, when it shows up The Downside Review, Vol. XLIII. Unfortunately that publication is available in snippet view only and the viewable snippet doesn’t show it. The search page showed this as an excerpt:
St Gregory’s response to the ‘power of darkness’ was pre-eminently the answer of prayer. This is also the answer of our recent … Is it not St Augustine who tells us that he ‘prays twice who sings his prayer’ ? St Gregory provided the classic form …
It shows up again in 1949 in Musart, Vols. 1-5, again sadly available only in snippet view that doesn’t show the quotation. The excerpt from the search page:
St. Augustine somewhere wrote that he who sings his prayer prays twice. But before this praising of God in song can be truly prayerful, the spirit of praise must run high in the soul. The song of the lips must first have been a song in the soul.
Both references speak of it in ways that sound as if it is already well-known quotation, but these are the earliest print references I could find, so I’m not sure what the original source is. I am confident that the original source is not St. Augustine.