Exceptions to the rule of adding an apostrophe “s” for the possessive form are the possessives of ancient proper names ending in “s.” Examples: Moses’ Law, Jesus’ parables, Euripides' tragedies, Xerxes' armies.

So the Lord said to him, “What is that in your hand?”

He [Moses] said, “A rod.”

The possessive of most singular nouns is formed by adding an apostrophe and an “s.” The possessive of plural nouns (except for a few irregular plurals that do not end in “s”) is formed by adding an apostrophe only. Examples: the horse's mouth, a bass’s stripes, puppies' paws, children's literature.

The em dash, often just called the dash, is the most commonly used of the dashes. To avoid confusion, no sentence should contain more than two dashes. A pair of em dashes sets off an amplifying or explanatory element. Commas, parentheses, or a colon may perform a similar function, but em dashes are often used for emphasis. Be careful not to overuse them though.

Hyphens and dashes all have specific uses.  They cannot be used interchangeably.

And when they say to you, “Seek those who are mediums and wizards,

who whisper and mutter,” should not a people seek their God?