Laravel Eloquent with() method works with ‘where’ but doesn’t work with ‘Model::find’ - development

Laravel Eloquent with() method works with ‘where’ but doesn’t work with ‘Model::find’

I want to have relationship between 3 tables, using Laravel Eloquent with() method.
this is my code (relationships are set in models):

    $request_form = RequestForm::find(7)->with(['RequestFormsCheck' => function ($q) {
        $q->orderBy("created_at", "DESC")->with('RequestFormsCheckOptions');
    }])->get();

    dd($request_form);

but this code returns all request forms except returning only id = 7
this is output:

Collection {#895 ▼
  #items: array:4 [▼
    0 => RequestForm {#796 ▶}
    1 => RequestForm {#797 ▶}
    2 => RequestForm {#798 ▶}
    3 => RequestForm {#799 ▶}
  ]
}

when I replace ->get() with ->first() it returns just request form, but its id is 1

but this code works great:

        $request_form = RequestForm::where('id', 7)->with(['RequestFormsCheck' => function ($q) {
            $q->orderBy("created_at", "DESC")->with('RequestFormsCheckOptions');
        }])->first();

        dd($request_form->toArray());

and this is its output (this is what I expect to get):

array:12 [▼
  "id" => 7
  "name" => "Jack"
  "email" => "jack@gmail.com"
  "telephone" => null
  "description" => "..."
  "site" => "http://branch.local/"
  "item_id" => 10
  "lang" => "en"
  "read" => 1
  "created_at" => "2018-05-15 11:09:47"
  "updated_at" => "2018-05-20 05:24:41"
  "request_forms_check" => array:1 [▼
    0 => array:8 [▼
      "id" => 1
      "request_form_id" => 7
      "type" => 2
      "request_forms_check_options_id" => null
      "description" => "custom note"
      "created_at" => "2018-05-15 11:48:36"
      "updated_at" => "2018-05-15 11:48:36"
      "request_forms_check_options" => null
    ]
  ]
]

these are my migrations:

    Schema::create('request_forms', function (Blueprint $table) {
        $table->increments('id');
        $table->string('name', 100)->nullable();
        $table->string('email', 100)->nullable();
        $table->string('telephone', 20)->nullable();
        $table->text('description')->nullable();
        $table->string('site', 100);
        $table->integer('item_id');
        $table->string('lang');
        $table->timestamps();
    });

and

    Schema::create('request_forms_check_options', function (Blueprint $table) {
        $table->increments('id');
        $table->string('title', 500);
        $table->timestamps();
    });

and this

    Schema::create('request_forms_checks', function (Blueprint $table) {
        $table->increments('id');
        $table->integer('request_form_id')->unsigned();
        $table->foreign('request_form_id')->references('id')->on('request_forms')->onDelete('cascade');
        $table->tinyInteger('type')->comment("1: option, 2:description");
        $table->integer('request_forms_check_options_id')->unsigned()->nullable();
        $table->foreign('request_forms_check_options_id')->references('id')->on('request_forms_check_options')->onDelete('cascade');
        $table->text('description')->nullable();
        $table->timestamps();
    });

from Laravel Questions and Answers https://laravelquestions.com/laravel/laravel-eloquent-with-method-works-with-where-but-doesnt-work-with-modelfind/
via Lzo Media