D&C 59

After stating some "thou shalt" commandments, the follows up with -

"And in nothing doth man offend God, or against none is his wrath kindled, save those who confess not his hand in all things, and obey not his commandments.
22 Behold, this is according to the law and the prophets; wherefore, trouble me no more concerning this matter."  (Doctrine and Covenants | Section 59:21 - 22)

In summary, God is offended when we fail to express gratitude for  his commandments and blessings and do not keep these commandments.  The very purpose of this life is to -

"...learn that he who doeth the works of righteousness shall receive his reward, even peace in this world and eternal life in the world to come."  (Doctrine and Covenants | Section 59:23)