why does ahab plead with starbuck not to accompany him when he meets moby dick

Ahab sees the homesickness in Starbuck's eye. He pleads with him not to follow because he does not want Starbuck to have the same fate.

"No, no; stay on board, on board!— lower not when I do; when branded Ahab gives chase to Moby Dick. That hazard shall not be thine. No, no! not with the far

away home I see in that eye!”