Matthew 22

It was the Saducees -

"...which say that there is no resurrection..." (New Testament | Matthew 22:23)

...on this occasion, in order to "tempt" or test the Savior, much like the Pharisees in order to turn the people and leaders against him, laid out a scenario of a woman that married seven men, then asked the Savior -

"Therefore in the resurrection whose wife shall she be of the seven? for they all had her." (New Testament | Matthew 22:28)

To which the Savior answered -

"Ye do err, not knowing the scriptures, nor the power of God.
30 For in the resurrection they neither marry, nor are given in marriage, but are as the angels of God in heaven." (New Testament | Matthew 22:29 - 30)

Many have taken that single statement to justify their belief that marraige and family does not continue in the eternal worlds. But the Lord had already taught with proper keys and authority -

"...Whatsoever ye shall bind on earth shall be bound in heaven..." (New Testament | Matthew 18:18)

and with such keys and authority -

"...What therefore God hath joined together, let not man put asunder." (New Testament | Matthew 19:6)

The Saducees were not interested in the doctrine of eternal marraige, they were only interested in justifying their belief that there be no resurrection. So the Lord, in reference to them, realizing they did not understand what it meant by keys and authority or in other words, wht "God had joined together", related only the principle of marraige that applied to them for He answered them, that in their case -

"...in the resurrection they neither marry, nor are given in marriage, but are as the angels of God in heaven." (New Testament | Matthew 22:30)

This same principle is taught in modern revelation -

"...if a man marry him a wife in the world, and he marry her not by me nor by my word, and he covenant with her so long as he is in the world and she with him, their covenant and marriage are not of force when they are dead, and when they are out of the world; therefore, they are not bound by any law when they are out of the world.
16 Therefore, when they are out of the world they neither marry nor are given in marriage; but are appointed angels in heaven, which angels are ministering servants, to minister for those who are worthy of a far more, and an exceeding, and an eternal weight of glory." (Doctrine and Covenants | Section 132:15 - 16)