John Murray on the regulative principle of worship in relation to John 4:24.

“The principle ‘in spirit and truth’ bears directly upon the content of worship. If worship must be consonant with the nature of God, it must be in accord with what God has revealed himself to be and regulated as to content and mode by the revelation God has given in holy Scripture. The sanction enunciated ('in spirit and truth') excludes all human invention and imagination and warns us against the offence and peril of offering strange fire unto the Lord. No principle more than this inculcates jealousy to ascertain that what we offer has the warrant of divine authority.” — John Murray, “The Worship of God in the Four Gospels,” in The Biblical Doctrine of Worship (1974), pp. 93-94 [not yet available on Log College Press]