Majma al-Zawaid 3817 — The great reward of illness

Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "On the Day of Resurrection the martyr will be brought and presented for reckoning. Then the one who gave charity will be brought and presented for reckoning. Then the people of trial will be brought, and neither a scale will be set up for them nor a register laid out for them. Reward will be poured upon them, until those who had well-being (in the world) will wish that their bodies had been cut with scissors (in the world), because of the excellent reward Allah Almighty will have given them (the people of trial)."
Al-Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains a narrator, Mujja'ah bin al-Zubayr, whom Ahmad declared thiqah (trustworthy) and al-Daraqutni (may Allah have mercy on him) declared da'if (weak).