Let a stranger praise you, and not your mouth/ let another man praise you, if he does not-then do it yourself/blow your own trumpet, if no one else will

It is permissible for a person to speak about themselves and their abilities when they are in a place where people do not know them, or where there is no one who can speak about their abilities and talents.

("They said to Rav Pappa: What is your name? He said to them: Rav Pappa. They said to him: But is it not stated, 'Let a stranger praise you, and not your mouth'? He said: And if there is no stranger—your mouth?" - Responsa of the Rashba, Rishonot, Peh; Sefer HaAggadah, 251; and also: "And behold, it is written, 'Let a stranger praise you, and not your mouth.' This is not difficult: here, in a place where they know him; there, in a place where they do not know him" - Rif, Bava Batra 5b; and also: "It is written, 'Let a stranger praise you, etc.' Here, in a place where they know him, etc. And Solomon did not state his words vaguely; the whole matter is explained in this verse: 'Let a stranger praise you'—that is, certainly when they know you, and not when they do not know you, when they cannot praise you; then it is permitted for your mouth to make you known" - Maharsha, Chiddushei Aggadot, Nedarim 62b)

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