2 sentences

1. 别用铅笔签合同。

   bié yòng qiān​bǐ qiān hé​tong.

   Don't sign the contract in pencil.

   Source: Tatoeba

2. 不要签空白合同。

   bù​yào qiān kòng​bái hé​tong.

   Do not sign blank contracts.

   Source: CCMatrix