Selling real estate is seriously ill, but verbally agreeing to sign for him in the real estate exchange is not allowed. According to relevant public information, oral consent cannot be used as the basis for the signature of legal agent, and authorization must be confirmed in writing. In the process of real estate transaction, the seller (that is, the owner of the house) needs to sign the relevant documents in person or entrust an agent to sign them on his behalf to ensure the legality and authenticity of the real estate transaction. If the seller is unable to sign in person due to illness or other reasons, he may entrust his relatives or friends or a professional agent to sign on his behalf. However, a written entrustment agreement must be signed before signing, and relevant fees shall be paid as required. On this basis, the agent can sign on behalf of the seller.