抛砖引玉pāo zhuān yǐn yù

抛出砖去，引回玉来。比喻自谦以粗浅的见解引出别人的高见。

例方才婢子费了唇舌，说了许多书名，原是抛砖引玉，以为借此长长见识。——清·李汝珍《镜花缘》

英throw out a brick to attract a jade; (fig) offer a few commonplace remarks by way of introduction so that others may come up with valuable opinions;