But they hamstrung her, so he said, "Enjoy yourselves in your homes (11:65)

﴿فَعَقَرُوهَا فَقَالَ تَمَتَّعُوا فِي دَارِكُمْ ثَلَاثَةَ أَيَّامٍ ۖ ذَٰلِكَ وَعْدٌ غَيْرُ مَكْذُوبٍ﴾
[ هود: 65]

11:65 But they hamstrung her, so he said, "Enjoy yourselves in your homes for three days. That is a promise not to be denied."

They denied what he said and harmed her, pushing their denial to extremes.
So Ṣāliḥ told them to enjoy life in their land for three days from the time they harmed her, then the punishment of Allah would come to them; and the coming of His punishment after that was a certain promise that there would be no possibility of denying, as it would come true.

But they killed her. So he said: "Enjoy yourselves in your homes for three days. This is a promise (i.e. a threat) that will not be belied."

phonetic Transliteration

FaAAaqarooha faqala tamattaAAoo fee darikum thalathata ayyamin thalika waAAdun ghayru makthoobin

Abdullah Yusuf Ali - Translation

But they did ham-string her. So he said: "Enjoy yourselves in your homes for three days: (Then will be your ruin): (Behold) there a promise not to be belied!"

Safi-ur-Rahman al-Mubarakpuri

But they slaughtered her. So he said: "Enjoy yourselves in your homes for three days. This is a promise (a threat) that will not be belied."

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