The ConnectionString property has not been initialized

Dim dataset As New DataSet
        Dim adapter As New SqlClient.SqlDataAdapter
        Dim command As New SqlClient.SqlCommand
        Dim cmd = New SqlCommand

        Dim con As New SqlConnection

        Try

            con.Open()
            cmd.Connection = con
            con.ConnectionString = "Data Source=lotus-pc\sqlexpress; Initial Catalog=LawyerSystem; Integrated Security= true "

            cmd.CommandText = "SELECT * FROM [users] WHERE (username='" + TextBox1.Text + "')AND (password='" + TextBox2.Text + "' )   "

            ' cmd.Connection = con
            cmd.ExecuteNonQuery()
            adapter.SelectCommand = command
            '  adapter.SelectCommand.Connection = con
            adapter.Fill(dataset, "0")
            Dim count = dataset.Tables(0).Rows.Count
            If count > 0 Then
                HomePage.Show()
            Else
                MsgBox("uncorrect", MsgBoxStyle.Critical)
            End If



        Catch ex As Exception
            MessageBox.Show("Error while inserting record on table..." & ex.Message, "Insert Records")
        Finally
            con.Close()
        End Try