I agree with @gibby 100 per cent also. However contrary to what @jhs said there are some professors at Harvard who get tenure because of their teaching ability. For example Malen with CS50 is a full professor. His class is legendary. I don’t think he does much research at all. The same can be said with Blitzstein in the stats department. He is a great teacher . Mankiws econ class has about 700 students and he also does a lot of research on the other hand