Quran 9:92

وَلَا عَلَى ٱلَّذِينَ إِذَا مَآ أَتَوۡكَ لِتَحۡمِلَهُمۡ قُلۡتَ لَآ أَجِدُ مَآ أَحۡمِلُڪُمۡ عَلَيۡهِ تَوَلَّواْ وَّأَعۡيُنُهُمۡ تَفِيضُ مِنَ ٱلدَّمۡعِ حَزَنًا أَلَّا يَجِدُواْ مَا يُنفِقُونَ ٩٢

Also excused are those who come to you wishing to be included with you, but you tell them, "I do not have anything to carry you on." They then turn back with tears in their eyes, genuinely saddened that they could not afford to contribute.