Luke 1:18

And Zacharias said to the angel, "How will I know this? For I am an old man and my wife is [also] very old."

Luke 1:34

And Mary said to the angel, "How can this be, since I have never had sex with a man?"

Luke 1:7

But they had no children, because Elizabeth was unable to bear offspring due to their both being very old.

Romans 4:19

Abraham's faith did not become weak [even though] he was about one hundred years old and considered his body almost dead and Sarah's womb incapable of conceiving a child.

Treasury of Scripture Knowledge

Summary

And Zacharias said unto the angel, Whereby shall I know this? for I am an old man, and my wife well stricken in years.

Whereby

Bible References

Whereby

Luke 1:34
And Mary said to the angel, "How can this be, since I have never had sex with a man?"

For

Luke 1:7
But they had no children, because Elizabeth was unable to bear offspring due to their both being very old.
Romans 4:19
Abraham's faith did not become weak [even though] he was about one hundred years old and considered his body almost dead and Sarah's womb incapable of conceiving a child.