Muwatta Malik, Book 58, Hadith 12 (USC-MSA)

Yahya related that Malik heard al-Ala ibn Abd ar-Rahman say, "Sadaqa does not decrease property, and Allah only increases a slave in worth for his restraint, and no slave is humble but that Allah raises him." Malik said, "I do not know whether this hadith goes back to the Prophet, may Allah bless him and grant him peace, or not."

وَعَنْ مَالِكٍ، عَنِ الْعَلاَءِ بْنِ عَبْدِ الرَّحْمَنِ، أَنَّهُ سَمِعَهُ يَقُولُ مَا نَقَصَتْ صَدَقَةٌ مِنْ مَالٍ وَمَا زَادَ اللَّهُ عَبْدًا بِعَفْوٍ إِلاَّ عِزًّا وَمَا تَوَاضَعَ عَبْدٌ إِلاَّ رَفَعَهُ اللَّهُ ‏.‏ قَالَ مَالِكٌ لاَ أَدْرِي أَيُرْفَعُ هَذَا الْحَدِيثُ عَنِ النَّبِيِّ صلى الله عليه وسلم أَمْ لاَ ‏.‏

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also referenced under: Book 58, Hadith 1855 (In-Book)