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:52:28 –

Indeed, we used to supplicate Him before. Indeed, it is He who is the Beneficent, the Merciful."  

indeed before, that is, in the world, we used to call on Him, worship Him, affirming His Oneness. Verily He is (read innahu as the beginning of a new ˹independent˺ sentence, even if it introduces the reason in terms of its import; or read annahu as a reason in terms of the ˹syntactical˺ order of the words) the Benign, the Beneficent, the True to His promise, the Merciful, One of tremendous mercy.
القرآن:٥٢:٢٨ –

إِنَّا كُنَّا مِنْ قَبْلُ نَدْعُوهُ ۖ إِنَّهُ هُوَ الْبَرُّ الرَّحِيمُ  

{إنا كنا من قبل} أي في الدنيا {ندعوه} نعبده موحدين {إنه} بالكسر استئنافا وإن كان تعليلا معنى وبالفتح تعليلا لفظا {هو البر} المحسن الصادق في وعده {الرحيم} العظيم الرحمة.