The Prophet ﷺ said to her, "Do not withhold, lest Allah withhold from you."
أخبرنا محمد بن آدم عن عبدة عن هشام بن عروة عن فاطمة
أن النبي ﷺ قال لها لا تحصي فيحصي الله عز وجل عليك
Bukhari reported it, in the Book of Zakat, chapter on encouraging charity and intercession in it, hadith no. 1433, from the hadith of Abdah bin Sulayman. And Muslim, in the Book of Zakat, chapter on urging spending and disliking counting what one gives, hadith no. 1029, from the hadith of Hisham, with the same wording. It is also found in Kubra, hadith no. 2331. Fatimah is the daughter of Mundhir.