As Meursault describes the bright sun reflecting off of the Arab man's blade, there is an alliterative repetition of words that start with the /s/ sound:
The scorching blade slashed at my eyelashes and stabbed at my stinging eyes. That’s when everything began to reel. The sea carried up a thick, fiery breath. It seemed to me as if the sky split open from one end to the other to rain down fire.
It is important to note that this alliteration is not present in Camus's original French: for example, "The scorching blade slashed at my eyelashes" is originally "Cette épée brûlante rongeait mes cils"—a French sentence that does not intentionally emphasize a specific sound. Nevertheless, as translators work to make a story intelligible to readers of a different language, some of the many tools at their disposal include different kinds of figurative language. Thus, while Camus himself is not responsible for the alliteration in the quotation above, it is an instance of figurative language that can still inform the reader's understanding of Matthew Ward's translation of The Stranger.
The extent of the sibilance, which is an alliteration of /s/ sounds, is overwhelming: "scorching," "slashed," "stabbed," "stinging," "sea," "seemed," "sky," and "split" all begin with the /s/ sound and sonically surround the reader. In fact, the /s/ sound is overwhelming for the reader in much the same way the heat and the glare is overwhelming for Meursault, clouding his thoughts and actions. "The scorching blade slashed at his eyelashes" only metaphorically—literally, the man did not slash at him with his blade, but rather the glare of the sun reflected into his eyes. Meursault, however, responds by shooting him as if he tried to slash at him with his blade. There is, then, a conflation of the figurative and the literal that produces a very real murder, and the alliteration present in the translated version of the scene infects the literal with the figurative just as Meursault blurs the lines between the two. The repeated /s/ sounds emphasize the sky and the sea in particular, both of which exude heat, according to Meursault. The alliteration thus highlights the most important physical sensations in the novella at the moment when those sensations are, to at least some extent, causing the climax of the story.