The deeds are considered by the intentions الأعمال بالنيات

1 - وعن أمير المؤمنين أبي حفص عمر بن الخطاب بن نفيل بن عبد العزى بن رياح بن عبد
الله بن قرط بن رزاح بن عدي بن كعب بن لؤي بن غالب القرشي العدوي رضي الله عنه قال سمعت رسول الله صلى الله عليه و سلم يقول : [ إنما الأعمال بالنيات وإنما لكل امرئ ما نوى . فمن كانت هجرته إلى الله ورسوله فهجرته إلى الله ورسوله ومن كانت هجرته لدنيا يصيبها أو امرأة ينكحها فهجرته إلى ما هاجر إليه ] متفق على صحته . رواه إماما المحدثين : أبو عبد الله محمد بن إسماعيل بن إبراهيم بن المغيرة بن بردزبه الجعفي البخاري وأبو الحسين مسلم بن الحجاج بن مسلم القشيري النيسابوري رضي الله عنهما في كتابيهما اللذين هما أصح الكتب المصنفة.
1. Narrated 'Umar bin Al-Khattab (May Allah be pleased with him), reported: Messenger of Allah (PBUH) said, "The deeds are considered by the intentions, and a person will get the reward according to his intention. So whoever emigrated for Allah and His Messenger, his emigration will be for Allah and His Messenger; and whoever emigrated for worldly benefits or for a woman to marry, his emigration would be for what he emigrated for".
[Al-Bukhari and Muslim].
Commentary: According to some Ahadith, the reason for this Hadith is that a person sent a proposal of marriage to a woman named Umm Qais, which she turned down saying that he should have to emigrate to Al-Madinah for it. Accordingly, he did it for this specific purpose, and the two were married there. On account of this event, the man came to be known among the Companions as Muhajir Umm Qais.
On the basis of this Hadith, 'Ulama' are of the unanimous opinion that the real basis of one's actions is Niyyah (intention) and everyone will be requited according to his Niyyah. It is true that Niyyah is founded in one's heart, that is to say, one has first to make up one's mind for what he intends to do and he should not express it verbally. In fact, the latter is a Bid`ah (innovation in religion) because no proof of it is found in Shariah.
The point which becomes evident from this Hadith is that Ikhlas (sincerity) is a must for every action. In other words, in every righteous deed, one should seek only the Pleasure of Allah; otherwise, it will not be accepted by Allah.