16 “Woe to you, blind guides, who say, ‘Whoever swears by the temple, it is nothing; but whoever swears by the gold of the temple, he is obliged to perform it.’
17 Fools and blind! For which is greater, the gold or the temple that sanctifies the gold?
18 And, ‘Whoever swears by the altar, it is nothing; but whoever swears by the gift that is on it, he is obliged to perform it.’
19 Fools and blind! For which is greater, the gift or the altar that sanctifies the gift?
20 Therefore he who swears by the altar, swears by it and by all things on it.
21 He who swears by the temple, swears by it and by Him who dwells in it.
22 And he who swears by heaven, swears by the throne of God and by Him who sits on it.
To swear by the altar was therefore to swear by all that was placed upon it, and to swear by the temple was to swear by Him who dwelt therein, even as to swear by heaven (a most frequent thing) is to take an oath by the throne of God and by Him who sits upon it. All such oaths were forbidden very definitely by the Lord on a former occasion (Matthew 5:33-37). — Ironside, page 305.
By making such distinctions the Pharisees were able to take an oath, but then absolve themselves of responsibility for fulfilling the oath. The one uninitiated in the distinctions would accept the oath of the Pharisee, not knowing that the oath had been couched in such phraseology that the Pharisee did not consider himself bound by it. Christ condemned such duplicity. — Pentecost, page 393.