57:7
ءَامِنُوا۟ بِٱللَّهِ وَرَسُولِهِۦ وَأَنفِقُوا۟ مِمَّا جَعَلَكُم مُّسْتَخْلَفِينَ فِيهِ ۖ فَٱلَّذِينَ ءَامَنُوا۟ مِنكُمْ وَأَنفَقُوا۟ لَهُمْ أَجْرٌۭ كَبِيرٌۭ
Believe in Allah and His Messenger and spend out of that in which He has made you successors. For those who have believed among you and spent, there will be a great reward.
Translation · Saheeh International
Tafsir
Ibn Kathīr (abridged)
Ordering Faith and encouraging spending
Allah the Exalted and Blessed orders having perfect faith in Him and in His Messenger, and that one should persist on this path adhereing firmly to it. Allah encourages spending from what He has made mankind trustees of, the wealth that you - mankind - have, that He has lent you. This wealth was in the hands of those before you and was later transferred to you. Therefore, O mankind, spend as Allah commanded you from the wealth that He entrusted to you for His obedience. Otherwise, He will hold you accountable and punish you for your ignoring what He ordained on you in this regard. Allah's statement,
مِمَّا جَعَلَكُم مُّسْتَخْلَفِينَ فِيهِ
(of that whereof He has made you trustees.), indicates that you - mankind -- will surrender this wealth to someone else. In this case, those who will inherit from you might obey Allah with their wealth, and thus acquire more happiness than you on account of what Allah has granted them. They might disobey Allah, and in this case you will have helped them commit evil and transgression. Imam Ahmad recorded that `Abdullah bin Ash-Shikhkhir said, "I came to Allah's Messenger ﷺ as he was reciting and saying,
أَلْهَـكُمُ التَّكَّاثُرُ
يَقُولُ ابْنُ آدَمَ: مَالِي مَالِي، وَهَلْ لَكَ مِن مَالِكَ إِلَّا مَاأَكَلْتَ فَأَفْنَيْتَ، أَوْ لَبِسْتَ فَأَبْلَيْتَ، أَوْ تَصَدَّقْتَ فَأَمْضَيْتَ؟»