Well I'd be interested in reading such a proof! Do you have a link, or do you want to make the argument yourself?
As I promised
Existence which it is assumed intellectually can be either necessary or possible. intellectually, no existent lies outside these two assumptions and every existent can't be assumed to be a possible existent because a possible existent always needs a cause. If all causes were possible existents, each one of them in turn requiring a cause, no existent would ever come into being. In other words an infinite regress of causes is impossible. Therefore an infinite series of causes must be compelled to terminate in an existent that isn't an effect of any other existent for example necessary existent.
More explanation
Possibility and necessity
All propositions whether simple or complex have two fundamental concepts (subject and predicate) for example in the following axiom ""the sun shines"" which establishes shining for the sun the sun is the subject and shining is the predicate. The establishment of a predicate for a subject has no more than three states: it could be impossible such as the number three is greater than the number four or it could be necessary such as the number two is half of the number four or it could be neither impossible nor necessary for instance the sun is above our heads.
In the terminology of logic the first proposition has the state of impossibility , the second proposition is given the attribute of necessity and the third state is considered as possible.
However in philosophy only existence is discussed and those things that are incapable of being ,of occurring and are impossible will never exist in the external world. For this reason philosophy regards existence from an intellectual respective as being either necessary or possible existence.
Necessary existence is known as an existence which exists in itself and doesn't depend upon another existent. Naturally such an existent will have no beginning and no end, because the non existence of something in a particular time is an indication that its existence isn't from itself. In order for it to come into existence it would need another existent which would be the cause or the condition for its realization. The absence of this condition or cause would be the reason for its annihilation.
Possible existence is known as an existent which doesn't exist in itself and depend on another existent in order for it to be realized.
These divisions which have been made through intellectual perception essentially disregard impossible existence , but they don't indicate whether a particular existent is a possible or necessary existent.
In other words the principles of this point of view can be conceptualized in three essential forms:
1 every existent is a necessary existent
2 every existent is a possible existent
3 some are necessary and some are possible existents.
On the basis of the first and third assumptions , the existence of a necessary existent is established
therefore the assumption that should be reviewed would be whether or not all existents are possible existents.
However by disproving this assumption (that all existents are possible existents) the existence of the necessary existent would be definitely and conclusively proven. The establishment of unity and other attributes must be proven with other arguments.
Therefore in order to disprove the second assumption we can say that
Every possible existent needs a cause and it's impossible to have an endless chain of causes. Thus the endless chain of causes is compelled to terminate at an existent that isn't in need of a cause for example the necessary existent.
This argument introduces other philosophical concepts which need a brief description.
Cause and effect
If an existent requires another existent and depends upon that other existent for its existence, then in philosophical terminology the caused existent is known as the effect and the other causative existent is known as cause. However it's possible that a cause can also be an effect and be a dependent existent that isn't absolutely free from need. If a cause is absolutely free from need and doesn't depend upon any other existent then it will be the absolute cause.
Possible existent doesn't exist in itself and has no alternative other than to depend upon another existent. Thus every predicate recognized for the subject is either established by itself or by means of other than itself. For example everything either shines in and of itself or requires something else for its illumination or everybody is oily in itself or needs oil for becoming oily. It's impossible for something in itself to not be illuminating or oily and not receive light or oil from something else while at the same time being oily and illuminating!
Hence the establishment of existence for a subject is either through its essence or by means other than itself and when it's not through its essence then it has to be by means of other than itself. Therefore every possible existent that is not realized through its essence is bound to be realized by means of other than itself which implies that it is an effect. This provides us with the fundamental intellectual principle that every possible existent needs a cause.
Very important point
Some imagine that the principle of causation means that all existents need a cause and therefore God needs a primary cause. They have overlooked the fact that the subject of the principle of causation is the existent in the possible sense and its effect Not in the existent in the absolute sense. Not all existents need a cause , only those which are dependable and are in need.
Proving that the first cause is unlimited and immaterial needs other arguments
For more information about infinit regress see
http://www.islamquest.net/en/archive/question/fa4182