This may sound obvious, but the subtleties around this topic are hugely important. When you hear of someone "hiring a buddy" the first thing that is likely to come to mind is the hiring of an incompetent crony. While that is certainly a dumb thing to do, that is not the pitfall into which smart managers fall. Hiring the completely competent friend with whom you have worked before, and know well, is where smart managers often fail.
Why? Because such a person often does not compliment your own strengths and weaknesses.
The problem is simple: with whom do we bond as friends? Usually people who are very much like ourselves. Conversely, who do you need as a trusted team member? Someone who is enough different from you that they fill in your own skill or attention gaps. Regarding their own development, what do they need in a supervisor? Someone who can show them what they don't know or help them develop where they are weak.
Not only is this not good for you as a manager, nor is it good for the friend you hire, it is bad for your current team. You and your newly hired friend have a history that your current team does not. They more often than not see the two of you as allies or worse yet a clique.
For your own sake, and that of your friends, hire for what you need and help your friends find good opportunities through referrals. Form your new team with its own dynamic. This approach is best for everyone.