Parashas Naso · Passuk 5:07
they shall confess the wrong that they have done. They shall make restitution in the principal amount and add one-fifth to it, giving it to the one who was wronged.
Chabad.org — English translation + Rashi
Source: Bava Kamma 110a.
English: “And they shall confess their sin” — it was taught: R’ Nasan says: This builds a prototype for all who are dying, that they require confession.
In context: The verse of confession in the context of restitution is generalized to the obligation of vidui before death.
Custom
Chazal establish from this verse that one who is dying must make confession.