Lord you know for how long Peter has been suffering with this problem in his hand so I pray you give him the healing he needs. Lord if he keeps irritating the situation by playing the guitar have him realize he needs to stay away from it and give it a long rest. That can be the reason for the tendinitis, or you may be giving him a sign that he should stay away from it and do something else less strenuous to his hand. Give him your peace, wisdom, and relieve from that pain. In Jesus Name I ask and thank you giving you all the Honor and the Glory Heavenly Father, Amen!