account_voucher_number_invoicesupplier/views/account_voucher_supplier_view.xml

<?xml version="1.0"?>
<openerp>
    <data>
        <record id="account_voucher_supplier_invoice_view" model="ir.ui.view">
            <field name="name">account.voucher.supplier.invoice</field>
            <field name="model">account.voucher</field>
            <field name="inherit_id" ref="account_voucher.view_vendor_payment_form"/>
            <field name="arch" type="xml">
                <field name="journal_id" position="after">
                    <field name="supplier_invoice_number" attrs="{'readonly':True}"/>
                </field>
            </field>
        </record>


    </data>
</openerp>