Messenger of Allah ﷺ said, "You will be rewarded for whatever you spend for Allah's sake even if it were a morsel which you put in your wife's mouth." (Using translation from Bukhārī 56)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ يَا سَعْدُ «إِنَّكَ لَنْ تُنْفِقَ نَفَقَةً تَبْتَغِي بِهَا وَجْهَ اللهِ إِلَّا أُجِرْتَ عَلَيْهَا حَتَّى اللُّقْمَةِ تَجْعَلُهَا فِي فِيِّ امْرَأَتِكَ»