1- Our father hoards his money in an unknown place and conceals it from us. What is the Sharee‘ah ruling on him doing so?
2- What is the status of the Hadeeth in which the Prophet, sallallaahu ‘alayhi wa sallam (may Allaah exalt his mention), said that difference of opinion among his Ummah is a mercy?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

The Sharee‘ah does not oblige a father to tell his children about his money or let them know where he keeps it. This decision is entirely up to him and children should not be insistent on this issue.

However, a father has to provide for his children according to what is acceptable, as long as they need it.  He also has to write his will and mention in it where he keeps his money, what he owes other people and what other people owe him. This way, when the father dies, his inheritors will be able to find his money, pay off his debts if any, and so on.

With regards to the aforementioned Hadeeth, "The difference of opinion among my Ummah is a mercy," it is a Mawdhoo' (fabricated) Hadeeth and falsely attributed to the Prophet, sallallaahu ‘alayhi wa sallam.  Al-Albaani explained that the scholars of Hadeeth did their best to find a chain of narrators related to this Hadeeth but found none.  He also rejected the opinion of Imaam As-Suyooti who believed that this Hadeeth might be mentioned in one of the books that have not reached us. Al-Albaani argued that this opinion is far from being sound because it implies that some Hadeeths of the Prophet, sallallaahu ‘alayhi wa sallam, have been lost, which is not proper for a Muslim to believe in.

Al-Munaawi quoted from As-Subki that this Hadeeth was unknown to the scholars of Hadeeth and they found no Saheeh (Authentic), Dha'eef (Weak) or even Mawdhoo’ (Fabricated) chain of narrators related to it.  Shaykh Zakariyya Al-Ansaari agreed with this opinion. Ibn Hazm also judged this Hadeeth as fabricated.

However, the sentence, "Difference of opinion among my Ummah is a mercy," was mentioned by many scholars who discussed difference of opinion, which makes its meaning ambiguous, especially since the texts of the Quran and Sunnah criticized such a difference. Therefore, Ibn Hazm explained that, had the difference in opinion been a mercy, then the agreement would have been discontent, which no Muslim could say.  Then, after he mentioned the evidence that difference in opinion is undesirable, he pointed out that, although the Companions disagreed about some matters, such criticism does not apply to them since all of them sought the pleasure of Allaah and what is right. Hence, those who were wrong would be rewarded once for their good intentions and would not be sinful because their mistake was not intentional and they spared no effort in search for the right. On the other hand, those who were right would be rewarded twice. This rule applies to every Muslim, until the Day of Judgment, in religious matters that are unknown after striving to reach what is right.

Indeed the mentioned criticism and threat are meant for those who abandon the texts of the Quran and Sunnah, which they know and clearly understand, and who blindly follow other opinions with the intention of creating disagreements and separation. In other words, the claim they believe in is the standard according to which the texts of the Quran and Sunnah are judged, so if the text agrees with that claim they adopt it, otherwise they abandon it.

There are another kind of people whose weak faith and impiety make them follow only scholars' opinions that satisfy their desires, and once they find such opinions they adopt them regardless of the rulings stated in the Quran and Sunnah.

Allaah Knows best.