Parents have highest right over their Offspring. Therefore, Islam bounded very strongly the offspring to do prayer for them i.e. to be habitual in Dua for Parents. Allah the al-mighty Himself pointed out the way mother gave birth to their child, and how they both, mother and father took care their children. Verily nobody can compensate that reward except Allah.

Here we have given some of the prayers that are considered to be in Dua for Parents according to Quran as well as proven from Sunnah-e-Rasool (SAWW).

If you are finding Dua for Parents for their forgiveness, you must recite,
 

Translation: "Our Lord! Forgive me and my parents, and (all) the believers on the Day when the reckoning will be established." [Quran: Surah Ibrahim, Verse 41]

Transliteration: “Rabbana ighfir lee waliwalidayya walilmumineena yawma yaqoomu alhisabu”

And if ones parents no longer remain in this world or be in the age of being unable to do something, one must recite Dua for Parents as following,
 

Translation: "My Lord! Bestow on them Your Mercy as they did bring me up when I was small." [Quran; Surah Al-Isra, Verse 24]

Transliteration: “… Rabbi irhamhuma kama rabbayanee sagheeran”