The Messenger of Allah ﷺ said, "When a slave fulfills the right of Allah and the right of his masters, he has two rewards."Ali said, "I narrated these two hadiths to Kaab."Kaab replied, "There is no reckoning upon him, nor upon a believer of modest means."
حدثنا أبو معاوية حدثنا الأعمش عن أبي صالح
قال رسول الله ﷺ إذا العبد أدى حق الله وحق مواليه كان له أجران قال فحدثتهما كعبا قال كعب ليس عليه حساب ولا على مؤمن مزهد
Its isnad is sahih. Muslim narrated it in 2:22, by way of Abu Muawiya from Amash, with similar wording, then narrated it again - without giving its wording - by way of Jareer from Amash. Its meaning (I mean the marfu hadith) has already appeared in the hadith of Ibn Umar several times, the first being 4673 and the last 6273.As for the statement of Kaab, it is the statement of Kaab Ahbar, and there is no proof in his saying, but they narrated it this way, attached to the hadith! And Kaab's word "al-muzhad" is with a damma on the meem, a saakin zay, and a kasra on the ha, from zuhd, meaning scarcity, and a thing described as zaheed means scanty. It is said, "the man became azhad," meaning his wealth became scarce.Ibn Athir erred in Nihayah 2:135, when he quoted this statement of Kaab Ahbar as though it were a hadith, saying, "And from this comes the hadith..."