{Privately, saying} (kat' idian hoti). Indoors the nine
disciples seek an explanation for their colossal failure. They
had cast out demons and wrought cures before. The Revisers are
here puzzled over Mark's use of hoti as an interrogative
particle meaning {why} where  Mt 17:19  has dia ti. Some of the
manuscripts have dia ti here in  Mr 9:28  as all do in  Mt
17:19 . See also  Mr 2:16  and  9:11 . It is probable that in
these examples hoti really means {why}. See Robertson,
_Grammar_, p. 730. The use of hos as interrogative "is by no
means rare in the late Greek" (Deissmann, _Light from the Ancient
East_, p. 126).