<StackPanel Orientation="Vertical"  Grid.Column="2" Margin="5 0 0 0">
                        <DatePicker  SelectedDate="{Binding  finishtWork}"/>
                        
                        <materialDesign:TimePicker     
                        Is24Hours="True"
                         Width="100"    >
                            <materialDesign:TimePicker.SelectedTime>
                                <Binding Path="finishtWork">
                                    <Binding.ValidationRules>
                                        <DataErrorValidationRule />
                                    </Binding.ValidationRules>
                                </Binding>
                            </materialDesign:TimePicker.SelectedTime>
                        </materialDesign:TimePicker>
                    </StackPanel>