Shaykh Ibn Uthaymeen said: “I encourage our brothers to frequently make du’a (supplication) for their parents, whether they are alive or deceased, because this is the way of righteous children who obey the command of Allah, the Most High: (And lower to them the wing of humility out of mercy, and say: ‘My Lord, have mercy upon them as they raised me when I was young’) [Surah Al-Isra: 24].” (Fatawa Nur ‘ala Al-Darb 27/1).