[38a bottom] When Rav Abba went from Bavel to Israel, he prayed that he would say something that would be accepted by the scholars there. When he got to Israel, he heard the Rabbis learning a Mishnah and tried to answer their question. In response, they laughed at his answer.
T’s lesson: No one is free from human responses and emotions [even the great sages of our Gemarah]. Rav Abba’s answer was not accepted because his prayer was not accepted due to the fact that Hashem decided against it. We should understand that Hashem always has His reasons and know what is truly best for us. Also, no prayer ever goes unanswered. Hashem responds, even though it may be in a different way than we may think or want at the time.