What is the ruling on swearing, "By Allah Almighty, I will not bear a child from you" for five years, coupled with the oath, "May I owe a million oaths if I go back on my oath and break it"? And is a million oaths required in the event of breaking it? And is there a sin for not breaking it?

If you broke your first oath, an expiation for an oath becomes binding upon you. As for your statement, "I owe a million oaths if I go back on my oath," scholars have differed on whether an oath is constituted by this phrasing. Some view it as not being an oath, while others consider it an oath that necessitates another expiation. The Malikis hold that one who breaks an oath is obligated to offer expiations equal to the number of their oaths, whereas the Hanbalis believe that a single expiation suffices regardless of how many times the oath is repeated, and this is the more preponderant view. Childbearing is a shared right of both spouses. If your wife desires to have children, then you must break your oath and offer a single expiation for an oath, and nothing else is binding upon you, according to the more correct opinion.