Singapore legislation
Section 9
of Oaths Act
Section 9
Proceedings and evidence not to be invalidated by omission of oath or irregularity
No omission to take any oath or make any affirmation, no substitution of any one for any other of them, and no irregularity whatever in the form in which any one of them is administered shall invalidate any proceeding or render inadmissible any evidence whatever in or in respect of which the omission, substitution or irregularity took place, or shall affect the obligation of a witness to state the truth.