Hm. It turns out Lin Chi said this and a whole lot more which actually conflicts with my own preferred understanding of this statement. Here's his commentary, from Wikipedia:
Wikipedia wrote: Followers of the Way [of Chán], if you want to get the kind of understanding that accords with the Dharma, never be misled by others. Whether you're facing inward or facing outward, whatever you meet up with, just kill it! If you meet a buddha, kill the buddha. If you meet a patriarch, kill the patriarch. If you meet an arhat, kill the arhat. If you meet your parents, kill your parents. If you meet your kinfolk, kill your kinfolk. Then for the first time you will gain emancipation, will not be entangled with things, will pass freely anywhere you wish to go.[2]
Those who have fulfilled the ten stages of bodhisattva practice are no better than hired field hands; those who have attained the enlightenment of the fifty-first and fifty-second stages are prisoners shackled and bound; arhats and pratyekabuddhas are so much filth in the latrine; bodhi and nirvana are hitching posts for donkeys.[3]
Obviously he was not opinionated.
I think what he's talking about is our own notions, however, it seems to me the exhortation applies as well to anyone wanting to be acknowledged as a Buddha/patriarch/arhat/parent/kinfolk. Perhaps most especially parents. Sort of a two way street...that is, we learn the labels, then have the roles filled at times, first by parents. And it takes a while to find and to forgive their feet of clay. Parents start out as Gods initially. The same thing might well happen with Buddha's and arhats, and all the rest...we learn the labels and perhaps someone fits, for a while, but Lin Chi is telling us its all bullshit. Slay the bastards. Interestingly, he said nothing about lovers.
I love his last line:" ...bodhi and nirvana are hitching posts for donkeys." - Yee Haw....