Do you have an iphone or an iPad? If so, you might get away with the built-in microphone on those, which I found to be quite good. I use my iPad to record meetings, and while people in the back of the room can be hard to pick up, it does pretty well with people sitting within a few feet. If you have an iPhone, you could just set it right in front of him, and the audio quality would be acceptable if the purpose is to simply record his words for later transcription.
I thnk some of you who are talking about the poor quality of internal mics are thinking about broadcast or podcast use. If the purpose here is simply to record the reminisces of a family member so you can refer back to it later or transcribe it, a lot of devices have internal microphones that will work fine. Sure, they’ll pick up room noise and be of lower quality, but the person’s voice should be intelligible enough for that purpose if the mic is close to them and you pick a quiet room for the interview.
If you’re looking for broadcast quality audio, then you want something that you can plug an external mic into. Then you could hook up a lavalier mic to his shirt can get high quality audio.
Or, if you have a laptop, you could get a USB microphone and use your laptop as the recorder. Or even an old-school dynamic microphone if your laptop has a standard microphone input. If the laptop has a built-in webcam, it’s probably got a built-in microphone as well which might work. Some laptops even have built-in noise canceling microphone arrays that are surprisingly good. Check to see what you’ve got.