Ashwin claimed his 500th Test wicket during the Rajkot Test against England.
During the third Test of the ongoing five-match series against England in Rajkot, Ashwin claimed his 500th Test wicket, becoming only the second Indian bowler after Anil Kumble to achieve this feat.
Speaking on his YouTube channel, De Villiers congratulated Ashwin for his incredible achievement and called the off-spinner one of the toughest bowlers he has faced.
"What a fantastic achievement! Congratulations Ash, you are one of the toughest bowlers I have ever played against - an incredible asset for the Indian cricket team with both bat and ball,” De Villiers said.
"He's been a stalwart, but not always getting enough credit for what he is and the role he plays in the Indian team. What a legend!"
The former Proteas skipper highlighted Ashwin's skills with the ball and also offered a piece of advice to England batters as to how to tackle him.
"The one thing that stands out is he's (Ashwin) a tall guy, so he's got natural variation and bounce. He's got subtle changes with his wrist - undercut more and get over the top a little bit more," De Villiers stated.
"He's also got the carrom ball and the leg-spin - bowls all kinds of deliveries. However, his strength is his accuracy, knowledge of the game and patience.
"Putting pressure on him is the best way to counter him. Make him guess the lengths he needs to bowl. You can do that by coming down the wicket, staying back deep in your crease, giving yourself a bit of room, coming across to the offside and working him to the leg side," he explained.
AB de Villiers had special praise reserved for Yashasvi Jaiswal, who has amassed 545 runs from six innings in the ongoing Test series at an average of 109 and a strike rate of 81.10, including two double hundreds and a half-century.
"What an incredible player! Very aggressive batting, and it makes the game look so easy. He's so good on the eye. He's always got the pressure on the bowlers; always looking to pounce.
"As an opening batter, he looks fantastic for the future, and he will be tested in different conditions around the world. But, he has undoubtedly got the ability, talent, skills and the mindset to counter whatever the challenges come his way," De Villiers said.
(With PTI Inputs)