قَالُوا۟ تَقَاسَمُوا۟ بِٱللَّهِ لَنُبَيِّتَنَّهُۥ وَأَهْلَهُۥ ثُمَّ لَنَقُولَنَّ لِوَلِيِّهِۦ مَا شَهِدْنَا مَهْلِكَ أَهْلِهِۦ وَإِنَّا لَصَٰدِقُونَ
Important Words:
لنبیتنه (We will surely attack him by night) is derived from بات. They say بات فی المکان i.e. he passed the night in the place.بیت الامر (bayyata) means, he performed the thing at night. بیت العدو means, he came upon the enemy suddenly, took him by surprise, attacked him by night or at night (Lane & Aqrab).
Waliyy means, an heir; one who demands retribution for murder; an avenger of blood (Lane).