Harden not (mh sklhrunhte). Prohibition with mh and first aorist (ingressive) active subjunctive of sklhrunw, late verb from sklhro (dried up, stiff, hard) as in Acts 19:9 ; Romans 9:18 . As in the provocation (w hn twi parapikrasmwi). Late compound from parapikrainw, late verb to embitter (para, pikro), found only in LXX and here and verse Romans 15 . It means embitterment, exasperation. For the simple verb pikrainw, to make bitter, see Colossians 3:19 . The reference is to Meribah ( Exodus 17:1-7 ). Like as in the day (kata thn hmeran). "According to the day" as in Acts 12:1 ; Acts 19:23 . Of the temptation (tou peirasmou). The reference is to Massah which took place at Rephidim.