From the shooting script of "Encounter At Farpoint":
There's nothing disrespectful in Riker's tone of voice, but he does leave an impression that he's not to be walked on either.
PICARD
I noticed in your envelope that Captain DeSoto thinks very highly of you. One curious thing, however, you refused to let him beam down to Altair IV?
RIKER
In my opinion, sir, Altair IV was too dangerous to risk exposing the captain.
PICARD
I see. A captain's rank means nothing to you.
RIKER
Rather the reverse, sir. A captain's life means a great deal to me.
PICARD
Let me postulate something here, Mister Riker. Isn't it just possible that you don't get to be a starship captain without knowing when it's safe to beam down or not? Isn't it a little presumptuous for a first officer to second guess his captain's judgment?
RIKER
Permission to speak candidly, sir?
PICARD
Always.
RIKER
You've been a first officer yourself. You know that assuming that responsibility must, by definition, include the safety of the captain. I have no problem with following the rules you lay down. But under no circumstances will I compromise your safety. If you have a problem with that, sir, you can put me back on the Hood before she leaves.
PICARD
You don't intend to back off that position?
RIKER
No, sir, I can't.