In Carl Sagan's Contact (the book, not the very good movie), Ellie is on the life-extension station with SR Hadden and about to land back on earth after the accident. I can't find the exact quoted exchange but it goes something like:
Hadden: Ellie, when you find them and talk to them, be VERY careful. These folks are old and their tolerances for risk may be alien to us.
Ellie: Well they sent us the Message, they obviously want to chat
Hadden: With beings that may be immortal or close to it, what we may consider a sure-fire bet may seem like an impossible risk to them. When they offer you something, you take it, you hear?
The closest approximation I can find is pp. 292--293. (I don't have a copy and haven't read it in about twenty years, so there may be a better approximation available.)
Hadden and Ellie have a brief discussion about the potential to market dying in space as a "really nifty last indulgence", whereupon Hadden segues to the topic of immortality and says the following:
"Now, I'm not bringing this up so I can boast. I'm bringing it up for a practical reason. If we're figuring out ways to extend our lifespans, think of what those creatures on Vega must have done. They probably are immortal, or close enough. I'm a practical person, and I've thought a lot now about immortality. I've probably thought longer and more seriously about it than anyone else. And I can tell you one thing for sure about immortals: They're very careful. They don't leave things up to chance. They've invested too much effort in becoming immortal. I don't know what they look like, I don't know what they want from you, but if you ever get to see them, this is the only piece of practical advice I have for you: Something you think is dead cinch safe, they'll consider an unacceptable risk. If there's any negotiating you get to do up there, don't forget what I'm telling you."
Hadden: Ellie, when you find them and talk to them, be VERY careful. These folks are old and their tolerances for risk may be alien to us.
Ellie: Well they sent us the Message, they obviously want to chat
Hadden: With beings that may be immortal or close to it, what we may consider a sure-fire bet may seem like an impossible risk to them. When they offer you something, you take it, you hear?
If someone can find the actual quote, thank you!