{Finding fault with them} (memphomenos autous). Present
middle participle of memphomai (cf. amemptos), old verb, in
N.T. only here and  Ro 9:19 . The covenant was all right, but the
Jews failed to keep it. Hence God made a new one of grace in
place of law. Why do marriage covenants so often fail to hold?
The author quotes in verses  8-12  Jer 38:31-34  (in LXX
 31:31-34 ) in full which calls for little explanation or
application to prove his point (verse  13 ). {I will make}
(sunteles(935c)). Future active of suntele(935c), old compound verb to
accomplish as in  Mr 13:4  Ro 9:28 . {A new covenant} (diath(886b)(886e)
kain(886e)). In  12:24  we have diath(886b)(8873) neas, but kain(8873) in
 1Co 11:25 . Kainos is fresh, on new lines as opposed to the
old (palaios) as in  2Co 3:6,14 ; 
eos is young or not yet
old.