Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "A woman should not observe a voluntary fast while her husband is present except with his permission, and she should not let anyone into his house while he is present except with his permission. And whatever she spends from his earnings without his instruction, half of its reward is his."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب القسم والنشوز / 14712