The Messenger of Allah ﷺ said, "When a woman spends from her husband's earnings without his explicit permission, she receives half of his reward."
حدثنا الحسن بن علي حدثنا عبد الرزاق أخبرنا معمر عن همام بن منبه قال سمعت
قال رسول الله ﷺ إذا أنفقت المرأة من كسب زوجها من غير أمره فلها نصف أجره
Bukhari reported it in the Book of Expenditures, chapter "The maintenance of a woman when her husband is absent from her," hadith no. 5360, and Muslim reported it in the Book of Zakat, chapter "What a slave spends from his master's wealth," hadith no. 1026, both from the hadith of Abdul-Razzaq, and it is in his Musannaf, hadith no. 7886, and in Sahifa Hammam bin Munabbih, hadith no. 76.