Jenkins pipeline with credentials

samplePipeline.groovy

node {
    stage('GetUserCredential') {
        // Requires Credential setup (MyCredentialID)
        withCredentials([[$class: 'UsernamePasswordMultiBinding', credentialsId: 'MyCredentialID',
                          usernameVariable: 'USERNAME', passwordVariable: 'PASSWORD']]) {

            sh '''
                set +x
                echo "$USERNAME" > output.txt
               '''
        }
    }
}