What are these three things Buddha cannot do?

According to this page from BuddhaNet, it is mentioned that there are three things Buddha cannot do. They are not mentioned in there and I don't know how reliable the source is. > 20. The Buddha is omniscient but he is not omnipotent. He is capable of innumerable feats but there are three things he cannot do. Also, a > Buddha does not claim to be a creator of lives or the Universe. I just found this question discussed on Dhamma Wheel. However, most of the replies are opinion-based.