Parshat Vayeara (hard to transliterate) starts with angels disguised as men visiting Avraham. The Ramban seems to say ( if I am reading it properly), that this is really a vision. The food brought to them is visions?, sarah’s response is a vision?
Whats the difference whether the angels are disguised as men and come to earth or they are merely visions. What is interesting to the Shikker Dovid is the Ramban cites what Abraham and sarah did in the vision. The focus is on their actions. The food they brought, the laughing of sara. TheShikker Dovid would like to suggest that angels or no angels, visions or no visions. We are real people must stress real actions to assist. Tangible acts. Whatever others are, angels or visions, our mandate is actions.