Sunan Abi Dawud 2880
سنن أبي داود#2880SahihNarrated Abu Hurairah:The Messenger of Allah (ﷺ) as saying: When a man dies, his action discontinues from him except three things, namely, perpetual sadaqah (charity), or the knowledge by which benefit is acquired, or a pious child who prays for him
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiSahih Muslim (1631)
In-book reference: 18:19