The phrase "sware up down" is often mistakenly spelled as "swear up and down." The correct spelling of the word is "sware," which is pronounced as /swɛr/. The "e" after "w" makes the vowel sound short, like "eh." Additionally, the word "up" is often mistakenly spelled as "up," but its correct spelling is "up." Lastly, "down" is spelled correctly. So the correct spelling of the phrase is "sware up down," pronounced as /swɛr ʌp daʊn/.