Jami` at-Tirmidhi Book 27, Hadith 11
"Three supplications are accepted , there is no doubt in them (about them being accepted): The supplication of the oppressed, the supplication of the traveler, and the supplication of his father against his son."
(Another chain) From Abu Bakr bin Hafs, from the Prophet (ﷺ), and it is similar, but he did not mention "from Ibn `Umar" in it. This is more correct than the Hadith of Abu Mu'awiyah, and Abu Bakr bin Hafs is Ibn 'Umar bin Sa'd bin Abi Waqqas (narrators in the chain of this Hadith.)
the Messenger of Allah said: "A son could not do enough for his father, unless he found him as a slave and purchased him to set him free."