Justin Bieber is reportedly not ready for a music collaboration with Selena Gomez.

According to a report in Hollywood Life, the Canadian pop star feels it would be a big step in their relationship, and he is not ready for it.

"They are working on songs together but there is no timetable to release anything soon," a source told the website. "They want it to be perfect, which is making things a little difficult because they only have one chance to release a song together for the first time."

"Justin also considers it to be a big step in their relationship if he releases a song with her," the insider added. "So he is not really ready to show that commitment."

Bieber had recently posted a black and white picture of himself in St Martin, along with the caption: "I've been on this break for too long #newmusic #back2work #vacationtimesup #longoverdue."

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I've been on this break for too long. #newmusic #back2work #vacationtimesup #longoverdue

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Meanwhile, the 21-year-old Come And Get It singer and Bieber are committed than ever in their relationship.

On 21 September, the couple were spotted together attending a service at Hillsong Church, in Los Angeles, California.

Bieber "uses her faith. That's why they always go to Bible study together, because he knows that when he asks for her forgiveness and tells her he wants to do right by her and by God that it works," another source previously told Hollywood Life.