When it is said
The Gelasian Sacramentary gives it to a priest blessing a house with water.
After the prayer, he blesses salt and puts it into the water. Wine and holy oil follow, and then he sprinkles the house with a sprig of hyssop.
In that service, “our coming in” meant the priest walking into the house. A family moving in might take the words as their own.
Where it comes from
No author known
From a Roman service book
The Gelasian Sacramentary is a service book put together about AD 750, probably near Paris, from older prayers of the Church of Rome. Its single copy is one of the few Western service books to survive from before the reign of Charlemagne.
The Gelasian Sacramentary, ed. H. A. Wilson (1894), introduction; The Cult of Saints, University of Oxford, E07005
“For a Family”
William Bright gave its first sentence in English in his Ancient Collects, a book of old prayers he chose from many service books for use in private prayer. The 1864 edition sets it under the heading “For a Family”.
William Bright, Ancient Collects and Other Prayers, third edition (1864), p. 104
What the words mean
Whose name goes in?
The Latin leaves a blank for a name, where the priest spoke the name of the person whose house it was. When you pray it, put in that person’s name, or your own if the home is yours.
The Scripture in it
Behold, I am sending an angel before you to protect you along the way and to bring you to the place I have prepared.
Bible text: Berean Standard Bible, public domain.
In Latin
Exaudi nos, Domine sancte, Pater omnipotens, aeterne Deus,
et mittere dignare angelum tuum sanctum de caelis, qui custodiat, foveat, protegat, visitet, et defendat omnes habitantes in hanc habitaculum famuli tui N.:
et praesta, quaesumus, ut sanctificatio sit domui huius noster introitus.
Donet cunctis intra eum habitu constitutos divinarum beatitudine largitatem, dominis ac familiae gubernaculum, ad custodiendam obedientiam et irreprehensibilem disciplinam,
infantibus bonae indolis gratiam, adultis immaculatam adolescentiam, senibus sanctam seriae conversationis aetatem, omnibusque longam ac sibi placitam senectutem:
et ita patrocinantibus sanctis perenni domui huic beatitudinem praestet, ut iugi super eam angelicae protectionis custodia perseveret.
Per Dominum.