فَإِذَا جَآءَ وَعْدُ أُولَىٰهُمَا بَعَثْنَا عَلَيْكُمْ عِبَادًا لَّنَآ أُو۟لِى بَأْسٍ شَدِيدٍ فَجَاسُوا۟ خِلَٰلَ ٱلدِّيَارِ ۚ وَكَانَ وَعْدًا مَّفْعُولًا

So when the promise for the first of the two came, We sent over you Our servants, of mighty prowess, so they went to and fro among the houses, and it was a promise to be accomplished.