51:23
فَوَرَبِّ ٱلسَّمَآءِ وَٱلْأَرْضِ إِنَّهُۥ لَحَقٌّ مِّثْلَ مَآ أَنَّكُمْ تَنطِقُونَ
Then by the Lord of the heaven and earth, indeed, it is truth - just as [sure as] it is that you are speaking.
The Winnowing Winds
فَوَرَبِّ ٱلسَّمَآءِ وَٱلْأَرْضِ إِنَّهُۥ لَحَقٌّ مِّثْلَ مَآ أَنَّكُمْ تَنطِقُونَ
Then by the Lord of the heaven and earth, indeed, it is truth - just as [sure as] it is that you are speaking.
Nearby ayahs help place verse 51:23 in sequence and meaning.
وَفِىٓ أَنفُسِكُمْ ۚ أَفَلَا تُبْصِرُونَ
And in yourselves. Then will you not see?
وَفِى ٱلسَّمَآءِ رِزْقُكُمْ وَمَا تُوعَدُونَ
And in the heaven is your provision and whatever you are promised.
هَلْ أَتَىٰكَ حَدِيثُ ضَيْفِ إِبْرَٰهِيمَ ٱلْمُكْرَمِينَ
Has there reached you the story of the honored guests of Abraham? -
إِذْ دَخَلُوا۟ عَلَيْهِ فَقَالُوا۟ سَلَـٰمًا ۖ قَالَ سَلَـٰمٌ قَوْمٌ مُّنكَرُونَ
When they entered upon him and said, "[We greet you with] peace." He answered, "[And upon you] peace, [you are] a people unknown.