Is the Hadith, "Whoever says 'Lā ilāha illallāh' (There is no deity but Allah) and prolongs it, will be forgiven four thousand major sins," authentic, and in which books was it mentioned?

The hadith mentioned in Kanz al-Ummal has a weak chain of transmission due to the presence of a liar, and it has been said to be fabricated because it mentions a great reward for a small deed, which is a sign of a weak or fabricated hadith.