Praise be to Allah!
(although I personally disagree tawassul through Status/Honour or what is call as "Sadqa-e-Tufayl" in Urdu can be considered a legitimate difference even after recognizing the difference among scholars on this, but it might be due to my own Jahl and I'll prefer to stay on safe side anyways)
I would like to know about their view on benefiting from grave (Fatwa which bro Ershad posted) what kind of "benefit" is it? and why can only shuyookh get the benefit while laymen will be led astray?
Yes, same. I personally don't hold the view of doing Tawassul, but as this is more of a personal matter rather than something to do "forbidding the evil" over. These are the words of the shaykh, the mujaddid, Muhammad b. `Abd al-Wahhab on this matter:
فكون بعضٍ يرخِّص بالتوسل بالصالحين وبعضهم يخصُّه بالنبي صلى الله عليه وسلم ، وأكثر العلماء ينهي عن ذلك ويكرهه ، فهذه المسألة من مسائل الفقه ، ولو كان الصواب عندنا قول الجمهور إنه مكروه فلا ننكر على من فعله ، ولا إنكار في مسائل الاجتهاد
"Some of the scholars allowed Tawassul through the righteous people and other (scholars) only allowed tawassul through the Prophet :saw2: (The shaykh attributed this to Imam Ahmad just before this) and most of the scholars prohibited Tawassul and disliked it. This matter is from the matters of Fiqh and although the correct opinion according to us is the opinion of the majority, that it is disliked- we do not rebuke the one who performs it (Tawassul) as there is no censuring in matters of Ijtihad."
Then the shaykh goes on to say, which is very important to note:
لكن إنكارنا على من دعا لمخلوق أعظم مما يدعو الله تعالى ، ويقصد القبر يتضرع عند ضريح الشيخ عبد القادر أو غيره يطلب فيه تفريج الكربات ، وإغاثة اللهفات ، وإعطاء الرغبات فأين هذا ممن يدعو الله مخلصاً له الدين لا يدعو مع الله أحداً ، ولكن يقول في دعائه : أسألك بنبيك ، أو بالمرسلين ، أو بعبادك الصالحين ، أو يقصد قبر معروف أو غيره يدعو عنده ، لكن لا يدعو ( إلا ) الله مخلصاً له الدين ، فأين هذا مما نحن فيه ؟
"However, our rebuking upon those who make du`a to the creation is greater than the one who calls upon Allah Ta`ala- as he (the one who calls upon the creation) travels to the grave whilst beseeching, (like) at the grave of sh. `Abd al-Qadir or other than him and seeking for hardships to be removed, (or) seeking aid from grief, (or) seeking to attain what is desired- and where is all this from the one who calls upon Allah, sincerely devoting his (entire) religion purely for the sake of Allah (and) not calling upon anyone other than Allah and says in his du`a: "I ask you (O' Allah) by your Prophet, or by the messengers, or by your righteous slaves" or he travels to Ma`ruf's grave or other than him to make du`a at the grave but he does not make du`a to anyone other than Allah, sincerely devoting his religion to Allah; where is this with regards to what we are upon (i.e. censuring those who make du`a to other than Allah)?"
Reference: مجموع مؤلفات الشيخ محمد بن عبدالوهاب (2/ 41) ط 1 ، دار القاسم