John 14:25,29 “These things I have spoken to you while being present with you.... And now I have told you before it comes, that when it does come to pass, you may believe."
Our Lord Jesus always told His disciples the events beforehand so that when these events came to pass they might believe Him and His other prophecies. Their faith in Him would definitely increase causing then to wait patiently and joyfully for the fulfillment of the next prophecy.
Mat 16:21 From that time Jesus began to show to His disciples that He must go to Jerusalem, and suffer many things from the elders and chief priests and scribes, and be killed, and be raised the third day.
Our Lord told His disciples again and again of His sufferings from the elders and chief priests, His death and finally His resurrection on the third day.
Mark 10:33-34 “Behold, we are going up to Jerusalem, and the Son of Man will be betrayed to the chief priests and to the scribes; and they will condemn Him to death and deliver Him to the Gentiles; and they will mock Him, and scourge Him, and spit on Him, and kill Him. And the third day He will rise again.”
This prophecy was so detailed and accurate of our Lord's betrayal to the chief priest and scribes, who condemned Him to death and then delivered Him to Pontius Pilate and the Roman soldiers, who mocked, scourged and spit on Him. They finally killed Him by crucifixion. When the disciples witnessed His sufferings and death, they should be rejoicing but instead the fear of being caught blinded them that they completely forgot His prophecy.
John 19:26 When Jesus therefore saw His mother, and the disciple whom He loved standing by, He said to His mother, “Woman, behold your son!”
John was the only disciple who was at the foot of the cross during His crucifixion (along with His mother Mary and a few women). The rest of the disciples were fearful and witnessed from a distance. He was not fearful of being caught or killed because of his faith and love for Jesus.
1 John 4:18 There is no fear in love; but perfect love casts out fear, because fear involves torment. But he who fears has not been made perfect in love.
Because John loved Jesus, so our Lord Jesus was very pleased to fulfill His promise by loving John [ he who loves Me...I will love him - John 14:21 ]. He wants us to realise that He is faithful to His words, and He will also love us if we love Him. Therefore, He kept declaring constantly in the bible that John was the disciple whom Jesus loved.
the third day He will rise again
John 20:8-10 Then the other disciple (John, the one Jesus loved), who came to the tomb first, went in also; and he saw and believed. For as yet they did not know the Scripture, that He must rise again from the dead. Then the disciples went away again to their own homes.
Though He told His disciples beforehand that after His sufferings and death, He would be resurrected. None of them believed Him for they did not understand His resurrection except for John (the one Jesus loved), whom our Lord had revealed the truth to him.
Brethren, when we love Jesus by keeping His words, He will love us and give us another Helper the Spirit of truth, Who will guide us into all truth so that we are free of worries, doubts, fears, etc. and then being led by the Spirit we can serve Him joyfully with truth and understanding.