avoir maille à partir

to be in an ongoing dispute with someone

Used when two people are at odds over something, with the friction rumbling on rather than blowing over.

Le voisin et moi, on a eu maille à partir à cause de la clôture.

My neighbour and I fell out over the fence.

Maille was a small bronze coin worth half a denier, the smallest unit of the old French currency. Since it couldn't be split between two people, having one to divide meant an argument was unavoidable.