فَهَلْ يَسْتَوِي مَنْ يَعِدُ وَمَنْ يَفِي؟
Can someone who merely promises be equal to someone who fulfils?
The speaker is not seeking information. After contrasting effort and mere speech, the question invites the listener to acknowledge that making a promise and keeping it are not equivalent. It functions as a denial framed as an interrogative.
In a genuine investigation of two persons, comparable wording could seek information. The rhetorical reading is justified here by the argument that precedes it and by the speaker’s evident purpose.