How do I contract a private Loan with a Colleague?

[Rasheed-mass Ali]

Greetings, Bigger Pockets community! I'm seeking your help in locating sample contracts, understanding crucial considerations, and learning how to modify contract terms. Specifically, I aim to create a zero-interest loan agreement spanning five months, culminating in a balloon payment. I'm curious about the important aspects, available contract templates, and potential blind spots in my knowledge. Any guidance or resources you can offer to aid me in this endeavor would be highly appreciated. Thank you in advance for your valuable insights!