"Then they all deserted Him and ran away." Mark 14:50
But is that one verse all the Gospels tell us about what the disciples did after Jesus' arrest? No, it certainly is not.
Luke 22 (italics mine for emphasis)
54 They seized Him, led Him away, and brought Him into the high priest’s house. Meanwhile Peter was following at a distance.
55 They lit a fire in the middle of the courtyard and sat down together, and Peter sat among them.
56 When a servant saw him sitting in the firelight, and looked closely at him, she said, “This man was with Him too.”
57 But he denied it: “Woman, I don’t know Him!”
58 After a little while, someone else saw him and said, “You’re one of them too!”
“Man, I am not!” Peter said.
59 About an hour later, another kept insisting, “This man was certainly with Him, since he’s also a Galilean.”
60 But Peter said, “Man, I don’t know what you’re talking about!” Immediately, while he was still speaking, a rooster crowed.
61 Then the Lord turned and looked at Peter. So Peter remembered the word of the Lord, how He had said to him, “Before the rooster crows today, you will deny Me three times.”
62 And he went outside and wept bitterly.
So after the arrest in the Garden, the Gospel of Luke relates how Peter denied the Christ, just as His Lord had prophesied. More painfully still, especially for Peter, we learn from the passage that Peter was close enough to Jesus in the high priest's house for him to see Jesus turn to look at him just after he had denied His Lord a third time. And it all happened because Peter had followed after Jesus and those who had arrested Him.
Here is a supporting account from another eyewitness, Jesus' beloved Apostle John:
John 18 (italics mine)
15 Meanwhile, Simon Peter was following Jesus, as was another disciple. That disciple was an acquaintance of the high priest; so he went with Jesus into the high priest’s courtyard.
16 But Peter remained standing outside by the door. So the other disciple, the one known to the high priest, went out and spoke to the girl who was the doorkeeper and brought Peter in.
17 Then the slave girl who was the doorkeeper said to Peter, “You aren’t one of this man’s disciples too, are you?”
“I am not!” he said.
18 Now the slaves and the temple police had made a charcoal fire, because it was cold. They were standing there warming themselves, and Peter was standing with them, warming himself.
In this Gospel we have a retelling of the denial, but the eyewitness John also tells us that both he and Peter were inside the high priest's home, which is where Jesus was being held. This shows us at least two of Jesus' apostles who are in close enough proximity to Jesus to risk being arrested themselves.
What about at the cross? Were there any apostles and disciples who actually saw Jesus crucified? John tells us that he and one of our most important eyewitnesses, Jesus' mother, were there. But they were not alone.
John 19 (italics mine)
25 Standing by the cross of Jesus were His mother, His mother’s sister, Mary the wife of Clopas, and Mary Magdalene.
26 When Jesus saw His mother and the disciple He loved standing there, He said to His mother, “Woman, here is your son.”
27 Then He said to the disciple, “Here is your mother.” And from that hour the disciple took her into his home.
And not only do we have the Apostle John and Jesus' mother, Mary, actually at the foot of Jesus' cross, but Jesus also speaks to them from it.
Now, Muslims believe that their "Allah" replaced Jesus with someone else on the cross. But what does this passage tell us? The passage reveals that the Man Who is on the cross is most definitely Jesus because, despite all the pain that He is suffering, He demonstrates His concern for His mother's welfare by entrusting her into the care of His closest friend, John, who is standing right beside her.
But what about at the time of His death? Were any of Jesus' disciples around to watch Him die?
Once more, we turn to eyewitnesses for the truth, rather than the claims of a non-eyewitness who lived 600 years later and 1,200 kilometers away.
Luke 23 (italics mine for emphasis)
44 It was now about noon, and darkness came over the whole land until three,
45 because the sun’s light failed. The curtain of the sanctuary was split down the middle.
46 And Jesus called out with a loud voice, “Father, into Your hands I entrust My spirit.” Saying this, He breathed His last.
47 When the centurion saw what happened, he began to glorify God, saying, “This man really was righteous!”
48 All the crowds that had gathered for this spectacle, when they saw what had taken place, went home, striking their chests.
49 But all who knew Him, including the women who had followed Him from Galilee, stood at a distance, watching these things.
Here is the proof that there was not just a tiny group of spectators, but a sufficiently large number of eyewitnesses who were physically present to see the Son of Man yield His spirit to the Father and take His last breath.
And because so many of them had watched Him die, would it come as a surprise that they would be stunned and amazed, even unbelieving at first when, just three days later, the Lord Jesus would rise again from the dead, just as He had said?
No, it wouldn't.
With special thanks to Marcia R. Buza for pointing out that last verse from Luke 23.
EyeWitness Report... The Crucifixion
Did Jesus Die on the Cross? I
Did Jesus Die On the Cross? II
Was Jesus Spared from Death, as Muslims Claim?