"Any Muslim man who frees a Muslim man, then it is his salvation from the Fire - each of his limbs suffices for a limb of himself. And any Muslim man that frees two Muslim women, then are his salvation from the Fire - each of their limbs suffices for a limb of himself. And any Muslim woman that frees a Muslim woman, then she is her salvation from the Fire - each of her limb suffices for a limb of herself."

Jami` at-Tirmidhi Book 20, Hadith 26