Al-Baqarah · 2:270

270. Whatever you spend, no matter how little, for the pleasure of Allah, or any action that you promise to do for Allah without having been required to do it, Allah knows of it and it will not be lost. He will give you a great reward for it. Those who do wrong by not fulfilling their obligations and overstepping Allah’s limits have no one to protect them against the punishment on the Day of Resurrection.