The Messenger of Allah ﷺ said, "The one who does not pay the zakat on his wealth will see his wealth appear to him on the Day of Resurrection in the form of a bald serpent with two black spots above its eyes. It will cling to him," or he said, "it will be wrapped around his neck, saying, 'I am your treasure, I am your treasure.'"
أخبرنا الفضل بن سهل قال حدثنا أبو النضر هاشم بن القاسم قال حدثنا عبد العزيز بن عبد الله بن أبي سلمة عن عبد الله بن دينار
قال رسول الله ﷺ إن الذي لا يؤدي زكاة ماله يخيل إليه ماله يوم القيامة شجاعا أقرع له زبيبتان قال فيلتزمه أو يطوقه قال يقول أنا كنزك أنا كنزك
Sourcing, its chain of transmission is sahih. Ahmad narrated it in 2/156 from Abu Nadr, through him. It is also in Kubra, no. 2260, and Ibn Khuzayma graded it sahih, no. 2257. Abdul-Aziz is Ibn Abdullah bin Abu Salama Majishun.