Al-Matalib al-'Aliyah 3570 — Surah al-Nisa

It is narrated from Muhammad bin al-Muntashir that a man said to Sayyiduna Umar bin al-Khattab (may Allah be pleased with him): "I know the most severe and most difficult verse in the Book of Allah Almighty (the Noble Qur'an)." On hearing this, Sayyiduna Umar (may Allah be pleased with him) lunged at him, struck him with his whip and said: "What is the matter with you? Did you dig into it so much that you came to know it?" Then the man went away, until, when the next day came, Sayyiduna Umar (may Allah be pleased with him) asked him: "Which is the verse you mentioned yesterday?" He said: "Did you give me a chance to tell you about it?" Then Sayyiduna Umar (may Allah be pleased with him) said to him: "I could not sleep the whole of last night because of this worry." The man said: "O Commander of the Believers! Allah, the Mighty and Majestic, has said: 'Whoever does evil will be recompensed for it' [Surah al-Nisa: 123]." (He explained that) there is none of us who does an evil deed except that he is recompensed for it. On hearing this, Sayyiduna Umar (may Allah be pleased with him) said to him: "Indeed, when this verse was revealed, (out of fear of Allah) neither food nor drink benefited us, until after that Allah, the Blessed and Exalted, granted a concession and ease by revealing (another verse), saying: 'And whoever does evil or wrongs himself and then seeks Allah's forgiveness will find Allah Most Forgiving, Most Merciful' [Surah al-Nisa: 110]."
The chain of this report is jayyid (good), and Imam Ishaq bin Rahwayh recorded it in his Musnad.