On the authority of Abu Harayrah (may Allah be pleased with him) from the Prophet (sallallahu 'alaihi wa sallam), who said:
Allah (mighty and sublime be He) said: Spend (on charity), O son of Adam, and I shall spend on you. It was related by al-Bukhari (also by Muslim).

عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ، أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ:
" قَالَ اللَّهُ: أَنْفِقْ يَا ابْنَ آدَمَ، أُنْفِقْ عَلَيْكَ ".

Arabic/English book reference : Hadith 11