Quran 67:13 from Surah Al-Mulk on Divine Marvels.
وَأَسِرُّواْ قَوۡلَكُمۡ أَوِ ٱجۡهَرُواْ بِهِۦٓۖ إِنَّهُۥ عَلِيمُۢ بِذَاتِ ٱلصُّدُورِ
English translation: And conceal your speech or proclaim it Indeed He (is the) All-Knower of what (is in) the breasts
Transliteration: wa-asirru qawlakum awi ij'haru bihi innahu alimun bidhati al-suduri