(IDEX Online) - British boxer Amir Khan has bought his son a $40,000 Rolex watch as a first birthday present.The former light-welterweight world boxing champion posted a picture of the boy, Muhammad Zaviyar, on social media, together with one of the Rolex Cosmograph Daytona, a timepiece described by its Swiss makers as "the ultimate timing tool for endurance racing drivers".Multi-millionaire dad-of-three Khan says the watch will be more of a collector's item for his son."Got my little boy his first birthday present, his watch collection needs to [be] on [point]," he posted on Instagram.Pic shows Amir Khan and his Instagram post