Is there a rule prescribing the absence of the -eth third person ending in late middle English?

Is there a rule prescribing the absence of the -eth third person ending in
late middle English?

Is there a rule prescribing the absence of the -eth third person ending in
late middle English ?
In the King James Bible, there are many verses which contain verbs in the
third person without the -eth a the end, for example :
Psalm 7:2 Lest he tear my soul like a lion, rending it in pieces, while
there is none to deliver.
Is there a particular reason for this ? Would "Lest he teareth" have been
correct ?
(I've been thinking that maybe it was a subjunctive, that wouldn't take
the ending or something of the sort)