2 U.S.C. § 191 : US Code - Section 191: Oaths to witnesses

Search 2 U.S.C. § 191 : US Code - Section 191: Oaths to witnesses

The President of the Senate, the Speaker of the House of
Representatives, or a chairman of any joint committee established
by a joint or concurrent resolution of the two Houses of Congress,
or of a committee of the whole, or of any committee of either House
of Congress, is empowered to administer oaths to witnesses in any
case under their examination.
Any member of either House of Congress may administer oaths to
witnesses in any matter depending in either House of Congress of
which he is a Member, or any committee thereof.