<I figured out that chandam is in accusative, bhikkhu in nominative. So the
sentence probably begins to say "The monk creates (janeti) a wish (chanda.m
) ". All the other words should be dative. And I do not understand how this
can
fit tohether.>
The function of the dative in this particular case is to denote the
goal of an action (the so-called dativus finalis of traditional school
grammar): the monk generates chandam so that that these unwholesome dhammas
do not arise.