Sub tuum praesidium

I say this prayer every day, in English. I occasionally say it in Latin. It is the oldest known prayer to Our Blessed Mother, going back, at least, to the third century.

We fly to Thy patronage, O Holy Mother of God; Despise not our petitions in our necessities, but ever deliver us from all dangers,O Glorious and Blessed Virgin. Amen.

Sub tuum praesidium confugimus,Sancta Dei Genetrix. Nostras deprecationes ne despiciasin necessitatibus nostris,sed a periculis cunctis libera nos semper,Virgo gloriosa et benedicta. Amen.

Here is a photograph of a papyrus, dated to 250 AD, containing the earliest earliest know written example of this hymn.

And here it is, with Gregorian chant notation from the Liber Usualis (1961), p. 1861. Latin lyrics sung by the Benedictine Monks of Santo Domingo de Silos (website in Spanish).