Muhammad b. al-Hasan al-Hurr al-`Amuli in ‎al-Fusul al-Muhimma vol 2‎, Book of Tahara, Chapters on the rules of the dead, wrote:

Chapter 18

(1210) 1 – قال الصادق عليه السلام: كل ما جعل على القبر من غير تراب القبر فهو ثقل على الميت.

1 – as-Sadiq عليه السلام said:  All that is put upon the grave other than the dirt of the grave, then it is a weight upon the deceased.

Chapter 19

(1211) 1 – قال علي عليه السلام: بعثني رسول الله صلى الله عليه وآله إلى المدينة فقال: لا تدع صورة إلا محوتها ولا قبرا إلا سويته ولا كلبا إلا قتلته.

1 – `Ali عليه السلام said: The Messenger of Allah صلى الله عليه وآله sent me to Madina, and he said: Do not leave any image but that you have erased it and no grave but that you have leveled it and no dog but that you have killed it.

(1212) 2 – وقال عليه السلام: من جدد قبرا أو مثل مثالا فقد خرج من الاسلام.

2 – And he عليه السلام said: Whoever renovates a grave or fashions an image, then he has exited from Islam.

What kind of fiqh rulings, important in our times, can we achieve from these ahadeth?

1) It’s prohibited to put on the grave dirt, more than from itself! Let alone to build shrines upon them.  As imaam as-Sadiq said:  (Everything except dirt from grave itself ) it is a weight upon the deceased”. Also we seen words of Ali (r.a), that prophet (sallalahu alaihi wa ala alihi wa sallam) ordered him to level graves. Similar hadith also exist in sunni books. Also we see imaam making takfir upon people who are renovating graves. SubhanAllah! What about millions which spend on the shrines, and their maintenance?!

2) It’s also very clear from two last ahadeth, that it’s prohibited to paint images. And HERE you can see picture gallery of imams, which so beloved by shias.

Compare these ahadeth with deeds of modern shias.