It is narrated from Hazrat Aisha that the Prophet (peace be upon him) said that one of her mukatab slaves came to her to pay the remaining amount of his contract of manumission. She said to him, "After today, you will not be able to come to me, but you must make jihad in the way of Allah obligatory upon yourself, because I heard the Prophet (peace be upon him) say: 'If the dust of jihad in the way of Allah mixes with the heart of any Muslim man, Allah makes the fire of Hell forbidden for him.'"