"Although no further details are given in the Qur'an, the Hadith indicate that one of Jesus' disciples volunteered to go in his place, and so Allah made him look like Jesus. Such devotion may seem surprising, but it is not uncommon among the followers of the prophets. When the Prophet Muhammad was preparing for the first battle against the Makkans, the head of the Madinians came to him and said: 'We want to keep you away from the battlefield. We can do without ourselves but we can't do without you.'Technically, the Qur'an is correct in that the Jews did not crucify Jesus; it was the Romans. However, there is also an interesting passage in the Qur'an. When the Madinans had killed some of the Meccans, who are their relatives, in battle, they were grieved. A verse was given to comfort them:There are two schools of thought as to what happened to Jesus after the aborted crucifixion. Some maintain that 'God raised him up to Himself' means that Jesus did not die a normal human death but was taken up into Heaven still in his body. Others maintain that the refererence is to Jesus being raised to a state of Prophethood in the eyes of the people, instead of being slandered as a dissident." (Kerry Brown and Martin Palmer ed. Essential Teachings of Islam, Arrow Books, 1990, p. 40-41)
Ye (Muslims) slew them not, but Allah slew them. And thou (Muhammad) threwest not when thou didst throw, but Allah threw, that He might test the believers by a fair test from Him. Lo! Allah is Hearer, Knower. (8:17)Here, although the Madinans were the ones fighting physically in the battle with the Meccans, the above verse said that it was Allah who did it, not them. This does not mean that they did not do it. Rather, Allah was behind it all.
Various in-depth articles on the interpretation of Surah 4:157 and related passages relevant to the question of the crucifixion of Jesus according to the Qur'an, on and off-site:
On the crucifixion according to the Bible: The Cross