Agnus Dei, qui tollis peccáta mundi, miserére nobis.
Agnus Dei, qui tollis peccáta mundi, miserére nobis.
Agnus Dei, qui tollis peccáta mundi, dona nobis pacem.

Agnus Dei (In Liturgy), a name given to the formula recited thrice by the priest at Mass (except on Good Friday and Holy Saturday) in the Roman rite. It occurs towards the end of the Canon, after the prayer „Hæc commixtio“, etc. Having finished saying this prayer, the priest covers the chalice with the pall, genuflects, rises, inclines his head (but not his body) profoundly towards the altar and, with hands joined before his breast (and not, therefore, resting on the altar), says with a loud voice: „Agnus Dei, qui tollis peccata mundi, miserere nobis“ (Lamb of God, Who takest away the sins of the world, have mercy on us), repeats the formula unchanged, and still a third time, substituting now „dona nobis pacem“ (grant us peace) for „miserere nobis“, meanwhile striking his breast thrice, once at each „miserere nobis“ and once at „dona nobis pacem“, with the right hand (the left hand resting throughout, from the first „miserere“, on the altar). In Requiem Masses, however, the formula occurs at the same part of the rite, but with the substitution of „dona eis requiem“ (grant them rest) for „miserere nobis“, and of „dona eis requiem sempiternam“ (grant them eternal rest) for „dona nobis pacem.“ In this case, the priest does not strike his breast, but keeps his hands joined before his breast throughout the whole formula. These rubrical details are given here for the reason that both the formula and the ceremonial accompanying it have undergone various changes in different ages and different places.