but the Messenger ﷺ said, “ʿUkkāsha has beaten you to it.”
Likewise, recall the woman who used to have seizures. She asked the Prophet ﷺ to supplicate to Allah on her behalf. He told her, “If you wish, I will pray that Allah cures you; but if you prefer, remain patient and Paradise will be yours.” She answered, “I will be patient, yet please pray that my body not be exposed.”
The conclusion is that being asked for supplication was a privilege unique to the Messenger ﷺ; for anyone else it is not legislated.
However, if a person asks another to pray and intends benefit for that other person—hoping that Allah will reward him for praying for his brother or that Allah will answer his plea—there is no blame. When someone prays for his brother in his absence, an angel responds, “Āmīn, and the same for you.” Deeds are judged by intentions. In this case the requester seeks benefit both for himself and for the one asked to supplicate, and deeds are indeed by intentions.
Pursuing a purely personal advantage, though, falls—as al-Shāfiʿī said—under the censured request. The Prophet ﷺ even pledged his Companions not to ask people for anything.