It is very unfortunate that people were heedless of praying for the quick reappearance of the leader of the time (May our souls be sacrifice for him). Had it been we are aware of our negligence to him we will realized that he was the first oppressed in this world.
We will mention below some instances where Imam (peace be upon him) was oppressed:
1-Hujjatul Islam Hajj Ismail Ashsharafi (may Allah be pleased with him) said: I went to the sacred place of Karbala to visit the lord of the martyrs (peace be upon him) I was then offering (Ziyarah) prayer and it occurred to me that visitor’s prayer is accepted if he offers it at the blessed head position of Imam Husein, I then request from Allah to grant me the opportunity of seeing my master, the leader of the time (peace be upon him) when I was still engaged offering my (Ziyarah) prayer, his beautiful Sun rises even though I didn’t knows him but my mind inclines towards him, I went closer and saluted him inquiring from him who are you?
He said: I am the first oppressed in this world! Then I didn’t understood what he meant by his statement and I inspire to myself that he may be one of the learned scholar in Najaf whom people did not pay him attention, that is why he feel to be the first oppressed in the world! He then out of my sight hence I believe that God has accepted my prayer and that was my master the leader of the time whom I have just met with.
2- Hujjatul Islam Sayyid Ahmad Musawi (he is among those who are eager to see the leader of the time (may Almighty Allah hasten his reappearance) he reported from Hujjatul Islam Sheikh Muhammad Ja’afar Al-Jawadi, the later was opportune to witness the awaiting Imam (may our souls be sacrifice for him) but he was very depressed, he inquired from him about his condition (peace be upon him) Imam replied him: my heart is filled up of blood, my heart is filled up of blood meaning that he is depressed (peace be upon him).
3- Imam Husein (peace be upon him) said to one scholar in Qum through unveiled world:
“Our Mahdi is oppressed in his time, so therefore preach and write about the personality Of Imam Mahdi (peace be upon him) to your last ability. Indeed preaching about the personality of this infallible Imam is like preaching on the personality of the whole infallibles (peace be upon them) because they were all offended in their infallibility, guardianship and in their Imamate, so far this is the time of our Mahdi you ought to preach about his personality”.
He (peace be upon him) concluded his speech by saying:
“I am still emphasising it again, preach and write a lot about our Mahdi. It is compulsory to write more than what was previously said about him because Our Mahdi is oppressed”.
 – Bustanul Wilayat 2: 18