contract/contract_mandate/views/contract_view.xml

<?xml version="1.0"?>
<odoo>

    <!--FORM view-->
    <record id="contract_contract_form_view" model="ir.ui.view">
        <field name="name">contract.contract form view (in contract_mandate)</field>
        <field name="model">contract.contract</field>
        <field name="inherit_id" ref="contract_payment_mode.contract_contract_form_view" />
        <field name="arch" type="xml">
            <field name="payment_mode_id" position="after">
                <field name="mandate_id"
                       domain="[('partner_id', '=', commercial_partner_id), ('state', '=', 'valid')]"
                       attrs="{'invisible': [('mandate_required', '=', False)]}"/>
                <field name="commercial_partner_id" invisible="1"/>
                <field name="mandate_required" invisible="1"/>
            </field>
        </field>
    </record>

</odoo>