David Beckham is such a proud dad, as he proved once again at the weekend when he shared the sweetest photo with three of his children to mark a special occasion.SEE: Romeo Beckham takes right after dad David in stunning photosThe 46-year-old took to his Instagram Stories, where he shared a throwback photo that saw David pose with his sons Brooklyn, Romeo, and Cruz when they were younger – alongside basketball legend Shaquille O'Neal, who turned 50 on Sunday.In the picture, David stood behind his boys and Shaq stood next to him, with one arm around his fellow sportsman, who he towered over.WATCH: David Beckham left impressed by Harper's new skillThe retired footballer shared the incredible snap alongside a caption that read: "Birthday boy @Shaq @Lakers."MORE: Victoria Beckham's retro honeymoon outfit gets fans really excitedSEE: Shirtless David Beckham unveils mind-blowing sauna at £12millon homeDavid's eldest son Brooklyn is now 23, while Romeo is 19 and Cruz is 17. The doting dad also shares daughter Harper, ten, with his wife, Spice Girls star-turned-designer Victoria.