Is the Hadith narrated from the Messenger of Allah, peace and blessings be upon him, in which it is stated: "Allah Almighty said: 'Whoever says "There is no god but Allah" a thousand times in Rajab, I will not punish him in the grave nor on the Day of Resurrection. And if I were to punish him, then I would not be his Lord.' He said it three times," authentic?

The hadith (definition) is not found in the books of Sunnah (definition), and most of the narrations concerning the virtues of Rajab are fabricated. It is not permissible to narrate fabricated hadiths except while clarifying their nature. Supplication (du'a) is prescribed, but specifying a particular supplication with a special virtue at a specific time requires authentic evidence.