Ibn Mas'ud (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) said: "The people who will be nearest to me on the Day of Resurrection will be those who supplicate Allah more often for me."[At-Tirmidhi]. (IT)
App reference (IT): Book 15, Hadith 2 (IT)
Arabic/English book reference (IT): Book 15, Hadith 1398 (IT)