Akshay Kumar is proud that his son Aarav bagged the first degree black belt in kudo, a Japanese martial art sport.

The 'Airlift' star, 48, took to Instagram to post an image of his 13-year-old son wearing a blue uniform with a black belt.

"Its a #SonDay all d way!After 9 yrs of training my son got his 1st degree black belt in Kudo #proudfather #overjoyed," he wrote.

It's a #SonDay all the way! Honestly I can't express my happiness, I've received the best gift ever today. My son started training when he was just four years old. And today, after nine years of hard work he got his 1st degree black belt in Kudo, Okinawa and Goju Ryu Karate Do! Some joys cannot be expressed in words, this one tops the list. But I'm feeling so proud, had to share it with you all 😀 #overwhelmed #cantstopsmiling #proudfather

A photo posted by Akshay Kumar (@akshaykumar) on May 8, 2016 at 2:15am PDT

For Aarav's mother Twinkle, it was the best Mother's Day gift.

"The biggest Mother's Day gift! Just got the news from his camp-All the years of nagging have paid off #BlackBelt," she wrote.

Akshay, who is himself a martial art expert, and Twinkle are proud parents to Aarav and daughter Nitara.