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:57:6 –

He causes the night to enter the day and causes the day to enter the night, and he is Knowing of that within the breasts.  

He makes the night pass into, He makes it enter, the day, so that it increases while the night diminishes, and makes the day pass into the night, so that it increases while the day diminishes. And He is Knower of what is in the breasts, of what it contains of secrets and convictions.
القرآن:٥٧:٦ –

يُولِجُ اللَّيْلَ فِي النَّهَارِ وَيُولِجُ النَّهَارَ فِي اللَّيْلِ ۚ وَهُوَ عَلِيمٌ بِذَاتِ الصُّدُورِ  

{يولج الليل} يدخله {في النهار} فيزيد وينقص الليل {ويولج النهار في الليل} فيزيد وينقص النهار {وهو عليم بذات الصدور} بما فيها من الأسرار والمعتقدات.