"The eye of a needle" is part of a phrase attributed to Jesus by the synoptic gospels:
...I tell you the truth, it is hard for a rich man to enter the kingdom of heaven. Again I tell you, it is easier for a camel to go through the eye of a needle than for a rich man to enter the
The parallel versions appear in Matthew 19:23-24, Mark 10:24-25 and Luke 18:24-25.
The saying was a response to a young rich man who had asked Jesus what he needed to do in order to inherit eternal life. Jesus replied that he should keep the commandments. To which the man stated he had done. Jesus responded, "If you want to be perfect, go, sell your possessions and give to the poor, and you will have treasure in heaven. Then come, follow me." The young man became sad and was unwilling to do this. Jesus then spoke this response, leaving his disciples astonished.
Some commentators have found it incredible to speak of a rich man's chance of being saved as being harder than threading a camel through a literal sewing implement. Consequently the phrase has inspired various interpretations.
The Quran uses this phrase to express the idea of something that is unlikely to happen:
To those who reject Our signs and treat them with arrogance, no opening will there be of the gates of heaven, nor will they enter the garden, until the camel can pass through the eye of the needle: Such is Our reward for those in sin.
Al-Araf (The Heights) 7:40