Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:67:13 –

And conceal your speech or publicize it; indeed, He is Knowing of that within the breasts.  

And ˹whether you˺ keep secret, O people, your speech or proclaim it, He indeed, exalted be He, is Knower of what is in the breasts, of what they contain: so how much more so ˹is He Knower˺ in the case of what you utter ˹openly˺ — the reason for the revelation of this ˹verse˺ was that the idolaters said to one another: ‘Speak secretly, and Muhammad’s god will not hear you’.
القرآن:٦٧:١٣ –

وَأَسِرُّوا قَوْلَكُمْ أَوِ اجْهَرُوا بِهِ ۖ إِنَّهُ عَلِيمٌ بِذَاتِ الصُّدُورِ  

{وأسِرّوا} أيها الناس {قولكم أو اجهروا به إنه} تعالى {عليم بذات الصدور} بما فيها فكيف بما نطقتم به، وسبب نزول ذلك أن المشركين قال بعضهم لبعض: أسرّوا قولكم لا يسمعكم إله محمد.