How authentic is the Hadith: "Whoever eats or drinks in the presence of a sick person has been fully rewarded," and what does it mean?

The aforementioned hadith was not found in the Sunan collections or books of hadith authentication and defects (kutub al-takhrij wal-ilal). Scholars also did not mention the prohibition of eating and drinking at a sick person's house among the etiquettes of visiting the sick. Ibn Hajar, in "Fath al-Bari," mentioned ten etiquettes for visiting the sick, including: not facing the door directly when seeking permission to enter, knocking gently on the door, not being vague about one's identity, not visiting at an inappropriate time such as when the patient is taking medicine, keeping the visit short, lowering the gaze, asking few questions, showing compassion, being sincere in prayer for the patient, giving the patient hope, advising patience, and warning against despair.