How sound is the circulating story about Umar ibn Al-Khattab meeting travelers on his journey, and his asking them about the greatest verse, the wisest verse, the most comprehensive verse, the most frightening verse, and the most hopeful verse in the Qur’an, and Abdullah ibn Mas'ud’s answer to them?

The mentioned story has a weak chain of narration (isnad). It was narrated in its entirety in Abu Tahir al-Silafi's "Al-Tuyuriyat" with a very weak isnad due to the presence of very weak narrators (Ibn Durayd, Al-'Ukli, Al-Haytham ibn 'Adi, Mujalid) and a break in the chain of narration (inqita') between Al-Sha'bi and Ibn Mas'ud and 'Umar.

It was also narrated by 'Abd al-Razzaq in his "Tafsir" and "Musannaf" with a broken chain of narration as well, for Ma'mar did not meet 'Umar ibn al-Khattab.

There is another narration from 'Abd al-Razzaq in his "Musannaf" with an authentic and connected chain of narration (isnad sahih wa muttasil), but it differs in the context of the story and does not include the mention of the Quranic verses. Instead, it focuses on the intelligence of the young man who answered 'Umar ibn al-Khattab.