On the recurrence of the paschal feast

God of everlasting mercy,
who, in the very recurrence of the paschal feast [(in ipso paschalis festi recursu)]
kindle the faith of the people you have made your own,
increase, we pray, the grace you have bestowed,
that all may grasp and rightly understand
in what font they have been washed,
by whose Spirit they have been reborn,
by whose Blood they have been redeemed.
Through our Lord Jesus Christ, [etc.] . . .

     Collect for the Second Sunday of Easter (with patent reference to the epistle, namely 1 Jn 5:1-6), taken word for word from the "Missa (in) die sabbato octava(e) paschæ" in the late 7th- or early 8th-century "Missale Gothicum" (so called). See, for example,

• Missale Gothicum (Vat. reg. lat. 317), ed. Leo Cunibert Mohlberg, Rerum ecclesiasticarum Documenta, Series major, Fontes 5 (Rome: 1961), 77;
• Missale Gothicum: das gallikanische Sakramentar-Cod. Vatican. Regin. Lat. 317-des VII.-VIII. Jahrhunderts, ed. Leo Cunibert Mohlberg (Ausburg: 1929), (a facsimile);
• "Missale Gothicum": a Gallican sacramentary (MS. Vatican. Regin. Lat. 317), ed. H. M. Bannister, vol. 1, Text and introduction, Henry Bradshaw Society 52 (London: 1917 [1916]), 89;
• Ancient liturgies of the Gallican church, ed. J. M. Neale and G. H. Forbes (Burntisland: 1855), 107;
• etc.

Mohlberg (1961), without variants:
Deus misericordiae sempiterne,
qui in ipso paschalis festae recursum
fidem sacratae tibi plebis accendis,
auge graciam quam dedisti,
ut digna omnes intellegencia conpraehendant,
quo labacrum abluti, quo spiritu regenerati,
quo sanguine sunt redempti:
per.

Bannister, without variants:
Deus misericordiae sempiterne
qui in ipso paschalis festę recursum
fidem sacratę tibi plebis accendis
auge graciam quam dedisti
ut digna omnes intelligencia conpręhendant
quo labacrum abluti, quo spiritu regenerati
quo sanguine sunt redempti
per. . . .

Neale and Forbes, without variants:
Deus misericordiæ sempiternæ,
qui in ipso paschalis festi recursu
fidem sacratæ tibi plebis accendis,
auge gratiam quam dedisti,
ut digna omnes intellegentia comprehendant,
quo lavacro abluti, quo Spiritu regenerati,
quo sanguine sunt redempti.
Per. . . .