Allah Ta‘ala describes the manner of the du‘aa of Hazrat Zakariyya (‘alaihis salaam) in the beginning of Surah Maryam. The purpose of this is to teach us the etiquette of du‘aa. The manner of his du‘aa was “nidaa’an khafiyya” (softly). Du‘aa should not be made by screaming and shouting, rather softly with extreme humility.
He then expressed his weakness before Allah Ta‘ala of his old age, but also explained that he desired a son to take charge after him. Hence, in du‘aa one should not challenge or show an attitude to Allah Ta‘ala. Instead, express your weakness and inability before Him. Even in this world, if you disobeyed a person and thereafter sought his forgiveness together with expressing your weakness and inability, his heart will melt and he will forgive you.