Three Prayers in Isaiah:

1. Isaiah for cleansing Isa 6:5). 

Answered (Isa 6:6-7),,

2. Hezekiah for deliverance Isa 37:16-20). 

Answered (Isa 37:36)

3. Hezekiah for healing and length of days Isa 38:3). 

Answered (Isa 38:5)

References to prayer (Isa 1:15; 7:11; 16:12; 26:16; 55:6-7).

References to groaning, sighing, crying, and entreating the Lord (Ex 2:11,23-25; 3:7,9; 10:16).