In the poem Lokasenna, the half-god Loki angrily flyts with the gods in the sea entity Ægir's hall. Thor does not attend the event, however, as he is away in the east for unspecified purposes. Towards the end of the poem, the flyting turns to Sif, Thor's wife, whom Loki then claims to have slept with. The god Freyr's servant Beyla interjects, and says that, since all of the mountains are shaking, she thinks that Thor is on his way home. Beyla adds that Thor will bring peace to the quarrel, to which Loki responds with insults.
Source from Wikipeida