وَإِذْ أَسَرَّ النَّبِيُّ إِلَىٰ بَعْضِ أَزْوَاجِهِ حَدِيثًا فَلَمَّا نَبَّأَتْ بِهِ وَأَظْهَرَهُ اللَّهُ عَلَيْهِ عَرَّفَ بَعْضَهُ وَأَعْرَضَ عَن بَعْضٍ ۖ فَلَمَّا نَبَّأَهَا بِهِ قَالَتْ مَنْ أَنبَأَكَ هَٰذَا ۖ قَالَ نَبَّأَنِيَ الْعَلِيمُ الْخَبِيرُ
“And [remember] when the Prophet confided to one of his wives a statement; and when she informed [another] of it and Allah showed it to him, he made known part of it and ignored a part. And when he informed her about it, she said, "Who told you this?" He said, "I was informed by the Knowing, the Acquainted."”
This is the specific asbab al-nuzul: Surat at-Tahrim's opening verses were revealed about this Hafsa/Maria incident, and the post directly quotes this ayah's closing line.