You may ask if there is money or units of account at this time that is not affected by inflation? The answer is the currency that has an intrinsic value which is equal to the value written on the money itself. That is the money which is formed in gold and silver. In Islam, this is called as Dinar and Dirham.

Perhaps your have a next question is about the truth of silver and gold or Dinar and Dirham is not affected by inflation or have a constant purchasing power throughout the period? To answer the question this description needs a little long as the following:

Al-Qur'an in the majestic, Allah said: "And likewise We did rouse them that they might question one another. One spokesman of them spoke, 'How long have you stayed here, some of them spoke, 'We stayed a day or part of a day'. Others spoke, 'Your Lord knows well how long you stayed', now then send one of you with this silver, to the city, then let him look for which food is the cleaner there and that he may bring for you provision from it, and let him be courteous and let him not inform anyone about you. " (Al-Kahf : 19)

In the paragraph above disclosed that they asked one of their friend to buy food in the city with their silver money.

Not explained the amount of the money, but clearly understand that it was silver money. If we assume the youth bring 2-3 pieces of silver money only, then this conversion to Rupiah is now about from Rp 100,000.

Now, with the same silver (1 Dirham now about Rp 33.900) we can buy food for some people.  After approximately 18 centuries, the silver purchasing power is relatively equal. Try to compare with the Rupiah, on the 70-year end as the high school boy which live in boarding house, I could eat in one month with only Rp 10.000. 

Is there now any boarding school boys can eat one month with the money only Rp 10.000? Certainly not. So just in less than 30 years our paper money has very very much difference value or purchasing power.

About the purchasing power of money on gold Dinar we can see from the following Hadith:

"Ali bin Abdullah narrated to us, Sufyan narrated to us, Syahib bin Gharqadah told us, he said: I hear people was telling stories about 'Urwah, that the Prophet SAW gave money to him one Dinar to buy a goat for him; Then, with the money he purchased two goats, and then selling it with a price of one Dinar. He brought home one Dinar and one goat. Prophet S.A.W. pray for him with the blessing in the trading. Even, if Urwah buy dust, he surely prosper "(HR. Bukhari)

From the hadith we can know that the market price of a goat on the Prophet, SAW period is one Dinar.

Conclusions drawn from this fact that Rasulullah SAW is a very fair, of course he would not tell 'Urwah to buy goats with the less or redundant money.

The second Fact is when 'Urwah sell one goat that he bought, he also sells at the price of one Dinar.

Indeed, previous 'Urwah successful purchase two goats with the price of one Dinar, this accomplishment because his ability in trading and in the hadith that he is specifically prayed by Prophet, SAW.

In other naration, someone had revealed that the price of goat up to 2 Dinar, this is possible in any where market. Because there is always any goat that small, medium and large.

If we consider the current price of a middle goat is one Dinar, a half Dinar for a small one and 2 Dinar for a large one at the Prophet SAW period, then now with a half up to 2 Dinar we can buy goat any where in the world.

This means that after more than 14 centuries Dinar has fixed purchasing power.

Now, try to compare us with the Rupiah. At the time of my elementary school (early 70's) my father to buy me a goat to be herded after school, the price of a goat at that time around Rp 8.000.

Now, after 35 years, we can buy a goat even the smallest one with Rp 8.000?  Ofcourse not.  Even we can not buy a chicken with the price of Rp 8.000.

Source : Gerai Dinar