Muadh said, "The last words I exchanged with the Messenger of Allah ﷺ were when I asked, 'Messenger of Allah, which deeds are most beloved to Allah, or which are the best?'He replied, 'That you die with your tongue still moist from the remembrance of Allah.'"
إن آخر كلمة فارقت عليها رسول الله ﷺ قلت: يا رسول الله أي الأعمال أحب إلى الله أو أفضل؟ قال: أن تموت ولسانك رطبا من ذكر الله.
No references are available.
Bukhari narrated it in Khalq Afal Abbad (281) - and this is his wording - and Ibn Hibban graded it sahih (818), as did Tabarani in Al-Kabir (20/107), and Musnad Shamiyin (192), and Ibn Sunni in Amal al-Yawm wal-Layla (2), all of them through various routes from Abdul-Rahman bin Thabit bin Thawban, from his father, from Makhul, from Jubayr bin Nufayr, from Malik bin Yakhamir, from Muaz bin Jabal, who mentioned it.Its chain is hasan because of Abdul-Rahman bin Thawban, for his hadith is hasan. There has been disagreement about several versions transmitted through Abdul-Rahman bin Thabit bin Thawban, but the sahih one among them is the one I have mentioned, and this is the version that Daraqutni favored in Al-Ilal (6/48–49). Ibn Hajar graded it hasan in Nataij Afkar, saying, "This is a hasan hadith."