Dream interpretation is a noble knowledge, which reveals future situations. The Holy Prophet said:

1 لَمْ یَبْقَ مِنَ النُّبُوَّۃِ ِاِلاَّالْمُبَشِّرَاتُ قَالُوْ ا وَمَاالْمُبَشِّرَاتُ قَالَ الرُّؤْیَاالصَّالِحَتہُ
"Nothing is left of the prophetism except Al-Mubashshirat." They asked, "What are Al-Mubashshirat?" He replied, "The true good dreams (that conveys glad tidings)."(Sahih Bukhari: 6990)

This hadith indicates that the believers now have nothing left, except for dreams that can reveal the future. As clouds indicate rain, true dreams point towards the future. The importance of true dreams is also evident from the fact that the first thing in the divine revelation that Holy Prophet  came across with were true dreams. In those days, interpretation of the dreams that the Prophet  saw were as clear as daylight 2 . After these circumstances, the Prophet  was inclined to take seclusion for the remembrance of God, by taking refuge in the cave of Hira. The significance of a true dream is also evident from the fact that it is called part of prophecy. As per one of the Hadith:

3 اَلرُّؤْیَا الصَّالِحَتُہ جُزْ ءٌ مِّنْ سِتَّتٍہ وَاَرْبَعِیْنَ جُزْ ءً مِّنَ النُّبُوَّۃِ
"A good dream is a part of the forty six parts of prophetism."(Sahih Bukhari: 6989)

From this hadith, one comes to knows that true dreams are a part of the science of prophethood. Even though prophethood concluded with the Last Prophet Muhammad , the knowledge of prophethood still remains.