Sayyiduna Amr bin Hazm (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "Whoever does not accept the concession of Allah Almighty bears sin as great as the mountains of Uhud."
Al-Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains Sulayman bin Amr bin Ibrahim al-Ansari, whom Ibn Abi Hatim mentioned, and he recorded no criticism (jarh) or commendation (ta'dil) of him.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصيام / 4938