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:92:18 –

˹He˺ who gives ˹from˺ his wealth to purify himself  

he who gives his wealth to purify himself, offering it as a ˹means of self˺ purification before God, exalted be He, by making this payment for the sake of God, exalted be He, and not for show or the sake of reputation, so that he ˹or the offering˺ stands purified in the sight of God. This ˹verse˺ was revealed regarding the truthful one (al-siddīq) ˹Abū Bakr˺, may God be pleased with him, when he purchased Bilāl ˹the Ethiopian˺, who was being tortured on account of his faith, and then freed him, whereat the disbelievers said, ‘He only did this in return for a favour which he ˹must have˺ owed him’, and so the following was revealed:
القرآن:٩٢:١٨ –

الَّذِي يُؤْتِي مَالَهُ يَتَزَكَّىٰ  

{الذي يؤتي ماله يتزكى} متزكيا به عند الله تعالى بأن يخرجه لله تعالى لا رياء ولا سمعة، فيكون زاكيا عند الله، وهذا نزل في الصدّيق ؓ لما اشترى بلالا المعذب على إيمانه وأعتقه، فقال الكفار: إنما فعل ذلك ليد كانت له عنده فنزلت.