How sound is the hadith "Punishment is lightened for Abu Lahab every Monday"?

No hadith with this wording has been found from the Prophet, peace and blessings be upon him. There have been mursal narrations and dream visions reported about the alleviation of punishment for Abu Lahab, but these visions cannot be deemed authentic, especially since they contradict what is established in the Holy Quran, that for disbelievers, "their torment will not be lightened" and "the supplication of the disbelievers is only in error."