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:28:16 –

He said, "My Lord, indeed I have wronged myself, so forgive me," and He forgave him. Indeed, He is the Forgiving, the Merciful.  

He said, remorsefully, ‘My Lord, I have indeed wronged myself, by killing him, so forgive me!’ So He forgave him. Truly He is the Forgiving, the Merciful, that is to say, the One Who has always possessed, and will always possess, these two attributes.
القرآن:٢٨:١٦ –

قَالَ رَبِّ إِنِّي ظَلَمْتُ نَفْسِي فَاغْفِرْ لِي فَغَفَرَ لَهُ ۚ إِنَّهُ هُوَ الْغَفُورُ الرَّحِيمُ  

{قال} نادماً {رب إني ظلمت نفسي} بقتله {فاغفر لي فغفر له إنه هو الغفور الرحيم} أي المتصف بهما أزلاً وأبداً.