Marcos 9

And he having come into the house, his disciples were questioning him by himself — 'Why were we not able to cast it forth?'

Y como él entró en casa, sus discípulos le preguntaron aparte: ¿Por qué nosotros no pudimos echarle fuera?

And when he was come into the house, his disciples asked him privately, Why could not we cast him out?

When he had come into the house, his disciples asked him privately, “Why couldn’t we cast it out?”