I start with Hume's ought; there is no ought from is.
More explicitly, there is no fact about the objective world from which it logically follows that any agent ought to do anything. However, note that this isn't complete; I have to use the modifier 'objective world.'
I use one assumption; value exists. Kindly keep in mind explicitly that value is inherently valuable. Since you desire things, I think this is a pretty safe assumption. (I have an irresistible urge to note that assumptions can only be challenged by self-contradiction.)
In the subjective world, there are values. Assume that right now, you value an ice cream. Because of Hume's ought, there can be no reason you ought not to go have some ice cream. However, I can construct a reason you should go get some ice cream; it would uphold your values and thus add value to the world.
That is, because of Hume's ought, normative statements can be constructed.
For a less toylike example, assume instead that you want some ice cream, but also value not consuming animal products. In this case, to have some ice cream would be to contradict your own values. I cannot construct a case that you ought to have ice cream, but I can construct a case that you ought not to have ice cream.
This is the only known way to validly construct normative statements. This also applies to any deities; while your values may be dependent on theirs for a variety of reasons, theirs will depend upon this structure; the fact that it is impossible to objectively contradict their values.
Now, you may object that because of this, morals are in a way voluntary. You are subject to them because you have opted in. However, all living things will opt in. Let me define life.
Life: Every object that can be assigned a goal is alive.
Living things will defend these goals, and if you manage to interrupt their goals, they will die. Another name for goal is value.
That is, if you can control your environment, make it conform to your goals, you have values.
"You ought not to follow ethics." This statement cannot be objectively supported. It can only be supported if you value not following ethics - if you value not following your values.
That is, to answer the question, "Ought I follow ethics?" with 'no' is a contradiction and by the law of excluded middle the only valid answer is 'yes.'
But perhaps 'ought' has no actual meaning at all, and as such the above question is meaningless. Equivalently, perhaps the question assumes a 'yes' answer to something that is, in fact, 'no.' However, this cannot be, because I would be able to construct a contradiction stemming from the physical consequences that question answered 'no;' the real consequences of that branch would contradict the logical consequences of this one. (Physicists use this principle to probe deeper logical levels all the time.)
And because all subjective facts can be reframed as objective facts (and vice-versa) Hume's ought is in fact a paradox. Are your values independent of my perceiving them, or not? Relative to me, they are objective, and thus the system of ethics that determines whether your actions are right or wrong is objective. (Kindly note explicitly the symmetry; my values are objective relative to you, and since the truth must not depend on perspective, all values must have properties consistent with objectivity. Though I should note that a different but equivalent argument applies if you take the axiom that subjectivity is first instead of objectivity.)
Nevertheless, there is truth behind Hume's ought. Yet it is strangely difficult to phrase it non-paradoxically without assuming my conclusion. "There is no ought that can be derived from non-value objects."