Meter las manos al fuego por alguien. “To put one’s hands in the fire for someone.” The phrase means to vouch for a person. A Mexican news site used it in a headline about a politician who would vouch for a colleague.
Dime con quién andas y te diré quién eres. “Tell me who you go around with, and I will tell you who you are.” The newspaper El Imparcial explains that the saying suggests that “las personas pueden ser juzgadas por quienes frecuentan” (people can be judged by the company they keep).