Then Musa got a fear within himself.
Moses harbored some fear.
Moses became fearful within himself
So Moses conceived fear in his mind
So he felt inner horror/fear in himself hiddenly/secretly Moses
Moses was overcome with fear
And Moosa sensed fear in his heart
And Moses conceived a fear in his mind
Now Musa (Moses) felt a sort of hidden fear in his heart
So Moses felt afraid in his mind (lest the people be misled by their glittering tricks)
So Moosa (Moses) conceived a fear in himself