There seems to be some discrepancy in how to write/pronounce the penultimate word of Tehillim (Psalms) 27:2.
According to Chabad.org, it is written:
ב. בִּקְרֹב עָלַי | מְרֵעִים לֶאֱכֹל אֶת בְּשָׂרִי צָרַי וְאֹיְבַי לִי הֵמָּה כָּשְׁלוּ וְנָפָלוּ:
Here, the word has a Kaf - with a Dagesh - which would be pronounced Kashəlu.
Yet, according to Mechon-Mamre.org, it is written:
ב בִּקְרֹב עָלַי, מְרֵעִים-- לֶאֱכֹל אֶת-בְּשָׂרִי: צָרַי וְאֹיְבַי לִי; הֵמָּה כָשְׁלוּ וְנָפָלוּ.
According to this, the word has a Chaf - no Dagesh - which would be pronounced Chashəlu (alt. Ḥashəlu or Khashəlu).
I've seen both used in printed Siddurim, and there seems to be no distinction drawn along Ashkenazi vs. Sepharadi tradition. The difference also does not seem to be based on different publishers using variant texts -- I've seen the same publisher use both forms consistently within one volume, but at odds with different editions of their Siddur (not different printings of the same book, but different editions of their Ashkenazi Siddur or their Sephardi Siddur). For example, the ArtScroll Siddur Kol Ya'akov writes it one way*, whereas the ArtScroll Siddur Yitzchak Yair writes it the other way*.
Is there some disagreement among codices or rabbinic sources that might explain this? Is one correct and the other a scribal error that's been missed and shared among several publishers?