Your proof of language proficiency.

Note: The law expressly requires “sufficient knowledge of the German language” (§ 9 Abs. 2 Satz 1 Nr. 7 AufenthG); pursuant to § 2 Abs. 11 AufenthG this corresponds to level B 1 of the Common European Framework of Reference for Languages. Under § 9 Abs. 2 Satz 2 AufenthG the requirements of Nr. 7 and 8 are deemed proven where an integration course has been successfully completed; the law also provides for exceptions (§ 9 Abs. 2 Sätze 3–5 AufenthG). Whether your proof is sufficient is assessed solely by your immigration authority.