Narrated Sahl bin Sa`d:
The Prophet Muhammad (ﷺ) said, “Whoever guarantees me (the chastity of) what is between his legs (i.e. his private parts), and what is between his jaws (i.e. his tongue), I guarantee him Paradise.” [Sahih al-Bukhari 6807]
Fawahish is the plural form of Fahisha, whose meaning, according to two opinions, could either be fornication and adultery or any bad deed that deserves punishment such as stoning, death, amputation (i.e. cutting a hand), etc.
In a variant hadith of the same narrator, the Prophet Muhammad said, “Whoever guarantees for me what is between his jaws and what is between his legs, I shall guarantee Paradise for him.” [Jami’ at-Tirmidhi 2408, graded Sahih by Darussalam]