When it is said
It is sung twice near the start of a moleben, a short Russian service of prayer, “for the increase of love and the uprooting of hatred and all malice”. A second form of that service, joined to prayers to the Mother of God, sings it too.
It is short enough to learn by heart and say at home, alone or with others.
Where it comes from
No author known
What a troparion is
A troparion is a short hymn that sums up a feast or a need in a few lines. This one belongs to the moleben for the increase of love. The service book names no writer and gives no date. Its readings include Jesus’s new commandment: love one another as I have loved you.
The hymn that follows it
The service also has a kontakion, a second short hymn. It asks Christ to set our hearts on fire with love for Him, so that we may love Him with all our heart, mind, soul and strength, love our neighbours as ourselves, and keep His commands.
The Scripture in it
A new commandment I give you: Love one another. As I have loved you, so you also must love one another.
And over all these virtues put on love, which is the bond of perfect unity.
If you love Me, you will keep My commandments.
Bible text: Berean Standard Bible, public domain.
In Church Slavonic
Союзом любви апостолов Твоих связавый, Христе,
и нас Твоих верных рабов к Себе тем крепко связав,
творити заповеди Твоя и друг друга любити нелицемерно сотвори,
молитвами Богородицы, Едине Человеколюбче.
From the Russian book of moleben services, in Church Slavonic, on Azbyka.ru, a Russian Orthodox website.