Justin Bieber calls Hailey his 'best friend' on 4th wedding anniversary

Sept. 14 (UPI) -- Celebrity couple Justin Bieber and Hailey Bieber are celebrating four years of marriage.

The 28-year-old singer and 25-year-old model marked the occasion Tuesday by dedicating loving tributes to each other on Instagram.

Justin Bieber shared a candid photo of himself and Hailey Bieber in bed with their dog.

"Happy anniversary to my best friend and wifey @haileybieber .. thanks for making me better in every way," he captioned the post.

Hailey Bieber posted a slideshow of photos, including a picture that shows herself and Justin Bieber kissing on their wedding day.

"4 years married to you. the most beautiful human I've ever known... love of my life. Thank God for you," she wrote.

Justin Bieber and Hailey Bieber legally married in September 2018 and held a second wedding with family and friends in South Carolina the next year.

Hailey Bieber discussed Justin Bieber in the September issue of Harper's Bazaar, saying they both have put the work in to make their marriage successful.

"He's still the person that I wanna be rushing back to," Hailey Bieber said of Justin Bieber. "I might fly somewhere and go do a job, but I can't wait to come back and hang out. And I feel like that's because of the effort that's been put in on both sides."

"At the end of the day, like, he's my best friend, but it still does take a lot of work to make it work," she added. "And then I know eventually, when kids come in the picture, that's going to be a whole other season of navigating how to make that work."

Justin Bieber announced last week that he will postpone the remainder of his Justice world tour to focus on his health.