Salam, how is the dua before entering the bathroom to be said? Is it the top or bottom one? Some books say it as the top one and others say it as the bottom one. Both of them have a slight variation which is a difference between of not having a dhamma (khubthi) and having a dhamma (khubuthi) on the baa in the word which I've put in parenthesis (one without a u and one with a u). Why is there a difference in this dua, if it's the same dua, shouldn't it be said the same way in all the books, why do some books say it differently? And which one is the correct one? Also, do we pronounce the kasra on the last letter of the last word and say wal khabaaithi or wal khabaaith because the transliteration says khabaaith even though you can see that the letter thaa has a kasra below it in both Duas shown below.
اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنَ الْخُبْثِ وَالْخَبَاﺋِﺚِ
اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنَ الْخُبُثِ وَالْخَبَائِثِ
Both words of Duaa that you have mentioned in your question stand correct. The slight difference in pronunciation is due to the word "Khubth" and "Khubuth" being used in both ways in Arabic language. This variation is due to the flexibility of reading Arabic word in different ways. The word "Khubth" is a noun from "Khabatha" and the word "Khubuth" is the plural of "Khabeeth". The end meaning of both is nearly same.
According to grammer rules, the last word "Khaba'ith" has to have Kasrah but when you pronounce it and stop there then you can read it both way: either with Jazam at the end or Kasrah. It does not affect the meaning at all.
And Allah knows best.
Mufti Ikram ul Haq
Fatwa Center of America