They said, "Take a mutual oath by Allāh that we will kill him by night, he and his family. Then we will say to his executor,1 'We did not witness the destruction of his family, and indeed, we are truthful.'"
Translation: Saheeh International (English)
1 i.e., the one responsible for executing his will and avenging his blood.
لَنُبَيِّتَنَّهُۥsurely, we will attack him by nightlanubayyitannahu
وَأَهۡلَهُۥand his familywa-ahlahu
ثُمَّThenthumma
لَنَقُولَنَّwe will surely saylanaqūlanna
لِوَلِيِّهِۦto his heirliwaliyyihi
مَاNotmā
شَهِدۡنَاwe witnessedshahid'nā
مَهۡلِكَ(the) destructionmahlika
أَهۡلِهِۦ(of) his familyahlihi
وَإِنَّاand indeed, wewa-innā
لَصَٰدِقُونَ(are) surely truthfullaṣādiqūna
Tafsir
They said to one another: “Each one of you should swear by Allah that we will go to him and the believers with him at night, then we will kill them and then say to the one responsible for avenging his blood: ‘We were not present at the murder of Salih or the murder of his followers, and we are truthful in what we have said’”.