Rocker Joel Madden has brushed off rumors of an impending split from wife Nicole Richie by publicly praising his "best friend" in celebration of Mother's Day (10May15).

The Good Charlotte star took to Instagram.com on Saturday (09May15) to express his gratitude for all Richie does for him and their two children, daughter Harlow, seven, and son Sparrow, five.

Alongside a photo of the couple, Madden wrote, "Happy Mothers (sic) Day to my best friend and partner in rhyme. Best wife, mother and friend a father and his kids could ever ask for."

Madden also dismissed divorce speculation in an earlier post by sharing a picture of his wife's feet, clad in socks bearing the couple's smiling faces.

He captioned it, "Sock Game Strong".

His declaration of love emerged online hours after Richie was photographed grocery shopping with new sister-in-law Cameron Diaz in Beverly Hills, California without her wedding ring.

Madden and Richie, who tied the knot in 2010, hit headlines recently amid unfounded reports suggesting they are heading for divorce.

The stars have yet to comment on the claims.