Mark 9:28-32

When He had gone indoors, His disciples began asking Him privately, “Why were we unable to drive it out?” He replied to them, “This kind [of unclean spirit] cannot come out by anything but prayer [to the Father].” They went on from there and began to go through Galilee. Jesus did not want anyone to know it, because He was teaching His disciples [and preparing them for the future]. He told them, “The Son of Man is to be betrayed and handed over to men [who are His enemies], and they will kill Him; and when He has been killed, He will rise [from the dead] three days later.” But they did not understand this statement, and they were afraid to ask Him [what He meant].