Hadith 5:453
'Umar ibn Ayyub narrated to us, from Ja'far, from Maymun, who said: Whatever you have of debt regarding what you hope for [of wealth], then calculate it, then deduct what is upon you, then pay Zakat on what remains.
حدثنا عمر بن أيوب عن جعفر عن ميمون قال ما كان من دين فيما ترجوه فاحسبه ثم اخرج ما عليك ثم زك ما بقي