{Of the angels} (pros tous aggelous). "With reference to"
(pros) as in  Lu 20:9 . So "of the Son" in verse  8 . Note
men here and de in verse  8  in carefully balanced contrast.
The quotation is from  Ps 104:4 . {Winds} (pneumata). "Spirits"
the word also means. The meaning (note article with aggelous,
not with pneumata) apparently is one that can reduce angels to
the elemental forces of wind and fire (Moffatt). {A flame of
fire} (puros phloga). Predicate accusative of phlox, old
word, in N.T. only here and  Lu 16:24 . Lunemann holds that the
Hebrew here is wrongly rendered and means that God makes the wind
his messengers (not angels) and flaming fire his servants. That
is all true, but that is not the point of this passage. Preachers
also are sometimes like a wind-storm or a fire.