One of the characteristics of Allah-sent Sharee'ah is its aptness and practicality in all times. The Law-giver is also the Creator of man who is well aware of the needs and nature, strength and weakness of man. The Qur'aan expresses the same idea in these words.

Should He not know what He created? And He is the Subtle, the Aware. (67:14)

The Divine Law makes an allowance for every contingency but when man takes up the task of framing laws for himself, he cannot take everything into consideration. A mixture of innovations and additions made from time to time make the religion so cumbersome and difficult that the people tend to get rid of the religion itself.

He hath chosen you and hath not laid upon you in religion any hardship, (22:78)
is a declaration of Divine Blessing, but it is taken away where innovations prevail. Its examples can be seen in elaborate orisons and rites where the bid'ah or innovation come to have a free hand.

Another feature of
Allah-given religion and its law is its universal applicability for it remains the same in every age and place. Any Muslim from one region may go to another part of the world, but he would not face any difficulty in the observance of religious obligations, nor would he require the help of any local mentor or guidebook. The bid'ah is, contrarily, never uniform. It is a product of local conditions, historical causes or personal prejudices and interests. It can, therefore, assume the shape of a different religion in every country or rather every region and town or may differ from house to house.

It was because of these considerations, perennial and universal in nature, that the Prophet  (sallallahu alayhi wasallam) had instructed his followers to follow his Sunnah and avoid bid'ah scrupulously. He had given the direction that:
"Whoever introduces something new in our religion that was not its part earlier, it shall be deemed as null and void."

Bukhaari, Aboo Daawood, Ahmad

"Avoid innovation in religion, for every innovation is a wickedness and every wickedness has its abode in Hell."

Tirmizi, Aboo Daawood, Ahmad

The Prophet  (sallallahu alayhi wasallam) also predicted that:
"Whenever people introduce some innovation in religion, an equivalent portion of Sunnah is taken away (from them)."