פירוש על ברכות 109:3

When he has the poor as his guests. Cf. "Let the poor be the members of thy household"; Abot i. 5, Singer, p. 185. Although this is the interpretation required by the context, Bacher (following Epstein) thinks that the dictum originally referred to the ritualistic purity of the daily meals; cf. A. P. A. I. p. 225 n. 2.