Narrated Ubai bin Ka`b:

Allah's Messenger (ﷺ) said, "Moses the Messenger of Allah," and then he narrated the whole story about him. Al-Khadir said to Moses, "Did not I tell you that you can have no patience with me." (18.72). Moses then violated the agreement for the first time because of forgetfulness, then Moses promised that if he asked Al-Khadir about anything, the latter would have the right to desert him. Moses abided by that condition and on the third occasion he intentionally asked Al-Khadir and caused that condition to be applied. The three occasions referred to above are referred to by the following Verses: "Call me not to account for forgetting And be not hard upon me." (18.73) "Then they met a boy and Khadir killed him." (18.74) "Then they proceeded and found a wall which was on the verge of falling and Khadir set it up straight." (18.77)

Narrated Ubai bin Ka'b:

that he heard Allah's Messenger (ﷺ) saying, "(Moses) said, 'Call me not to account for what I forget and be not hard upon me for my affair (with you)' (18.73) the first excuse of Moses was his forgetfulness."