Do you know if a French equivalent exists for this expression? In general, idioms being the expression of popular wisdom, whose roots are shared by most European countries (the Bible, Greek and Latin literature), most English proverbs have French equivalents, which are often identical, but for this one, I’ve been racking my brains and can’t think of a suitable translation. It’s very odd, especially as its Latin origin makes it a prime candidate for a French adaptation:

Latin gaudium est miseris socios habuisse penarum, it is a comfort to the wretched to have companions in woe.

1349 R. Rolle Meditations on Passion in C. Hortsmann Yorkshire Writers (1895). I. 101 It is solace to haue companie in peyne.

Oxford Dictionary of Proverbs