It is Sunnah to ask others to pray for us with the hope that it will be accepted, and this has been mentioned in the Quran and Sunnah, such as:
• Allah’s statement: “They said, ‘O our father, ask for us forgiveness of our sins.'” [Yusuf, 12:97] This is a request for supplication (dua).
• The Prophet (peace be upon him) said: “The supplication of a Muslim for his brother in his absence is readily accepted.” [Narrated by Muslim]
• Umar ibn Al-Khattab (may Allah be pleased with him) reported: “I asked the Prophet (peace be upon him) for permission to perform ‘Umrah, and he granted it. He said, ‘Do not forget us in your supplications, my brother.’ Umar said that there are few words that have ever pleased him more than that. In another narration, the Prophet (peace be upon him) said: ‘Include us in your supplication, my brother.'” [Narrated by Ahmad, Abu Dawud, and Ibn Majah]
• Ibn Majah reported from Umar (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) said: “When you visit a sick person, then ask him to supplicate for you, for his supplication is like the supplication of the angels.” It was said in Al-Zawa’id: Its chain of narration is authentic, and its narrators are trustworthy, although it is disconnected (munqati).
And there are other evidences to support this.
Fatwa by Dr. Khālid Naṣr