Doing Sajdah to the grave
Visiting graves (Ziyarat-e-Quboor) is a Sunnah. Visiting graves of the Auliya (saints) leads to even more blessings. However, Sajdah (prostration) is only for the Lord Almighty Allah Ta'ala. Prostrating before the creation is forbidden (Haraam). If someone really prostrates to the graves, they should stop doing so. We should not ever do anything which is forbidden by the Shariah. The Auliya don’t like it as well.