They said, "Take a mutual oath by Allah that we will kill (27:49)

Almuntakhab Fi Tafsir Alquran Alkarim

They mutually agreed and resolved under oath (their kind of oath) to launch an attack upon him -Saleh- and his people by night to finish them off and rid the town of them and then declare their innocence to his next of kin and insist on their statement, thus: We, they would say, were never present at the scene of the massacre of his people and this is the truth

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(27:49) They said to one another, "Let us pledge on an oath by Allah that we shall attack Salih and his household by night, and then tell his guardian *63 that we were not even present at the time his family were killed: we are telling the truth." *64

They said, "Take a mutual oath by Allah that we will kill meaning

*63) "The guardian": the chief of the Prophet Salih's tribe, who, according to the ancient tribal tradition and custom, could make a claim to blood vengeance. The same was the position in Makkah of the Holy Prophet's uncle, Abu Talib. The Quraish were hesitant that if they attacked and killed the Holy Prophet, Abu Talib, the chief of Bani Hashim, would come out with a claim to blood vengeance on behalf of his clan .
*64) This precisely was the kind of plot which the Makkan chiefs of the clans were devising against the Holy Prophet, and they devised the same ultimately on the occasion of migration (Hijrah) to kill him. They decided that men from all the clans would attack him in a body so that the Bani Hashim could not hold any one of the clans as responsible for the murder, and, therefore, would fmd it impossible to fight all of them at one and the same time.
 

They said, "Take a mutual oath by Allah that we will kill meaning in Urdu

انہوں نے آپس میں کہا "خدا کی قسم کھا کر عہد کر لو کہ ہم صالحؑ اور اس کے گھر والوں پر شب خون ماریں گے اور پھر اس کے ولی سے کہہ دیں گے کہ ہم اس خاندان کی ہلاکت کے موقع پر موجود نہ تھے، ہم بالکل سچ کہتے ہیں"