Tafsir of Al-Hajj 22:49

It is said: "I strove (sa‘aytu) in the affair of so-and-so," whether one intends to rectify it or corrupt it through one's effort.

"And those who strive against Our verses [to cause failure]..." ‘Ajazahu (to render incapable) is synonymous with sabaqahu (to outstrip/outrun), because each of the two parties seeks to render the other incapable of catching up to them. When one outstrips the other, it is said: "He rendered him incapable (a‘jazahu or ‘ajazahu)."

The meaning is: They strove in the matter of the verses by corrupting them through disparagement—calling them magic, poetry, and myths—and by discouraging people from them, believing themselves to be outstripping or competing in their claims, hoping that their plot against Islam would be completed for them.

If you ask: The logical structure would seem to be, "I am only a warner and a bringer of glad tidings," because both groups are mentioned afterward.

I reply: The discourse is directed toward the polytheists. "O people" is a call to them; they are the ones referred to in the verses: "Have they not traveled through the earth?" and they are the ones described as being hasty. The believers and their reward are only mentioned to provoke the polytheists' anger.