Late Shaykh ul-Islam has also narrated from Sayyid Bahbani, the Friday Prayer leader:

One day I came out to pray in the holy Masjid ul-Haram. On the way I faced a serious peril, but the Almighty Allah saved me and I set out for the Masjid safely and in health. There were two piles of musk melons near the Masjid gate, and the vendors were selling them. I inquired about the price· and learnt that the two piles were priced differently. I thought that I would buy one on my return.

Then I entered the Masjid and started praying, but soon my mind strayed as to which quality and quantity of melons I should buy; and the prayers were completed in this way.

After prayers, as I was stepping out of the Masjid, a gentleman entered. He came to me and said in my ear: Is it appropriate for you to recite the prayer of musk melons in the house of the God, who saved you from death? I immediately realized my folly and began to tremble in fear. Later I tried to meet him again, but could not find him anywhere.

There are numerous stories resembling stories 36 and 38, including the story on page 311 of Qisas ul-Ulama, in which Late Tankabani says:

It is mentioned among the merits of Sayyid Razi that once he was praying behind his brother, Sayyid Murtaza Alam ul-Huda; while bowing down (Ruku), he separated his intention and prayed solitary.

After prayers, people asked the reason for it. He said: When I bowed down, I saw the prayer leader, my brother, Sayyid Murtaza contemplating on an issue related to menses. He was absolutely focused on that and was immersed in a sea of blood. So I changed my intention to solitary.

It is mentioned in some books that Sayyid Murtaza said: Before coming for prayers, a lady had asked me about an issue concerning menses and I was fully occupied in its solution.

Presence of mind in prayer is very important, even though it is not among its necessary conditions and even if one prays without it, his prayer is technically correct and his duty is fulfilled, but we should know that a prayer without presence of mind is like a body without soul. Just as a body is useless without life, a prayer without presence is not rewardable and it will not earn proximity of God, except that part, which was performed with full concentration. That is why fifty percent of some prayer and one fourth of some and even one-tenth of some prayer is worthy of acceptance.

In Al-Kafi, it is narrated from Imam Ja'far as-Sadiq ('a) that it is possible that a person may pray for fifty years, but not even two units are accepted.

O Allah, I seek Your refuge from prayer, which does not rise up to You and from the act, which is of no use.