Hawzah News Agency – Imam Sadiq peace be upon him says:

لا يَزالُ إبليسُ فَرِحاً ما اهتَجرَ المُسلِمانِ، فإذا التَقَيا اصطَكَّت رُكبَتاهُ وتَخَلّعَت أوصالُهُ‏، ونادَى‏ يا وَيلَهُ، ما لَقِيَ مِن الثُّبُورِ؟!

'Satan continues to be happy as long as two Muslims forsake each other, and when they reconcile again his knees tremble and his joints break apart, and he screams out 'Woe unto me, I am perished'.'

Source: al-Kafi, v. 2, p. 346, no. 7