Majma al-Zawaid — Hadith 3774

Zirr bin Hubaysh narrates: We came to Sayyiduna Safwan bin Assal al-Muradi, and he asked: "Have you come to visit?" We said: "Yes." Then he said: The Prophet (peace and blessings be upon him) said: "Whoever goes to meet his believing brother remains immersed in mercy until he returns, and whoever goes to visit his believing brother in his illness remains in the gardens of Paradise until he returns."
Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains Abd al-A'la bin Abi al-Musawir, who is da'if (weak).