7th Heaven, Season 6

Matt:
[after Ruthie finds out that Matt got married] Could you Ruthie? Could you keep it a secret that you know we got married last night? Could you just forget and never say anything? I mean, because that's a terribly big secret for a little girl to keep for the rest of her life and I don't even know if I should ask you.

Ruthie:
You can ask me anything, horse or no horse. You're my brother and this is a good secret, the best secret I've ever heard. And we both know I know them all. I can do it. As God as my witness, I will never, ever tell this secret to anyone, cause I owe it to you for being my big brother for 11 years. I love you. I respect you. You have my word of honor. This stays with me.