Confucius said: “The Way makes no progress. I will take a raft and put out to sea. I’m sure Zilu will come with me.” When he heard this, Zilu was delighted. Confucius said: “Zilu is much braver than I am, but we can’t get any materials for our raft.”
In all likelihood, Confucius is playing a lighthearted joke on his disciple Zilu, who was known for his fearlessness and impetuosity (and ultimately died as a result of them).
Some translators such as Legge have tried to mine more meaning out the last line of the passage (無所取材), suggesting that the character材 (cái/materials) should be replaced by the homonym 裁 (cái/to judge), as in: “He (Zilu) does not exercise his judgment upon matters.”
But to me such contortions don’t, er, hold water. The literal translation is quite strong enough to stand on its own right, even if the joke itself isn’t a particularly good one. Nobody said Confucius had to be a great comedian as well as a great philosopher.