Majma al-Zawaid — Hadith 9527

Sayyiduna Ka'b bin Ujrah (may Allah be pleased with him) narrates: One day the Prophet (peace and blessings be upon him) said to his Companions: "What do you say about a person who is killed in the path of Allah?" The people said: "He will go to Paradise." The Prophet (peace and blessings be upon him) said: "If Allah wills, he will go to Paradise." The Prophet (peace and blessings be upon him) said: "What do you say about a person who dies, and then two upright men stand and say: 'We know nothing of him but good'?" The people said: "Allah and His Messenger know best." The Prophet (peace and blessings be upon him) said: "If Allah wills, this one too will go to Paradise." The Prophet (peace and blessings be upon him) asked: "What do you say about a person who dies, and then two upright men stand and say: 'We know of no good in him'?" The people said: "He will go to Hell." The Prophet (peace and blessings be upon him) said: "He is a sinner, and Allah Almighty is Oft-Forgiving, Most Merciful."
Al-Tabarani recorded it. Its chain contains a narrator, Ishaq bin Nistas, who is da'if (weak).