(Say: "Swear you not...") meaning, do not swear this oath.
(obedience is known.) It was said that the meaning is, your obedience is known, i.e., it is known that your obedience is merely verbal and is not accompanied by action. Every time you swear an oath you lie. This is like the Ayah:
(They swear to you that you may be pleased with them...) 9:96 And Allah says:
(They have made their oaths a screen (for their evil actions).) 58:16 It is part of their nature to tell lies, even in the issues they choose, as Allah says:
(Have you not observed the hypocrites who say to their friends among the people of the Scripture who disbelieve: "If you are expelled, we indeed will go out with you, and we shall never obey any one against you; and if you are attacked, we shall indeed help you." But Allah is Witness that they verily are liars. Surely, if they are expelled, never will they go out with them; and if they are attacked, they will never help them. And if they do help them, they will turn their backs, and they will not be victorious.) 59:11-12 Then Allah says:
(Say: "Obey Allah and obey the Messenger...) meaning, follow the Book of Allah and the Sunnah of His Messenger .
(but if you turn away,) if you ignore what he has brought to you,
(he is only responsible for the duty placed on him), conveying the Message and fulfilling the trust.
(and you for that placed on you.) accepting that, and venerating it and doing as it commanded.
(If you obey him, you shall be on the right guidance.) because he calls to the straight path,
(The path of Allah to Whom belongs all that is in the heavens and all that is in the earth. ..) 42:53
(The Messenger's duty is only to convey in a clear way.) This is like the Ayat:
(your duty is only to convey and on Us is the reckoning.) 13:40
(So remind them -- you are only one who reminds. You are not a dictator over them.) 88:21-22