What is the authenticity of the story circulated online about a man who entrusted his wife's pregnancy to God during the time of Omar ibn al-Khattab, then sees fire emanating from her grave to find his son crawling around his deceased mother, and hears a voice saying: "O you who entrusted his Lord, take your trust, and had you entrusted her mother to Him, He would have preserved her"?

The story mentioned in the question was narrated by Ibn Abi Dunya and Al-Hakim Al-Tirmidhi, on the authority of Umar ibn Al-Khattab, may Allah be pleased with him, concerning a man who was granted a child after he entrusted to Allah what was in his wife's womb, who had passed away. A fire appeared on her grave, and the grave was found open with the child crawling around it. The chain of narration for this hadith (definition) contains trustworthy narrators, except for Ubaid ibn Ishaq, whom Al-Bukhari, Abu Hatim, and the majority of hadith scholars deemed weak. However, Ubaid was not the only one to narrate this hadith, as he was corroborated by Uthman ibn Zufar, who is considered truthful.