Is it permissible for a person, who vowed to offer two Rak`ahs (units of prayer) everyday for Allah`s sake, to do so after the Fajr (dawn) prayer?
In principle, a vow should be fulfilled as it was originally intended, and if its time lapses then, it should be fulfilled at any time because of the vow. Therefore, it is permissible to offer them after the Fajr prayer, and there is no prohibition in doing so. However, it is preferable for him to offer these two Rak`ahs at some other time to avoid the disagreement amongst the scholars in this regard.
I am a wholesale gold trader. My clients are retail gold shop owners. I sell them gold jewelry and ornaments on credit, and they repay me in weekly installments over a period of two months or more. The payments are made in cash for the labor charges and for the gold they owe me. In return, they may give me either cash or used gold.
It is not permissible to sell gold or silver on an installment basis or with a deferred payment; rather, immediate exchange is required. The Messenger of Allah (PBUH) said: "Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, and salt for salt, like for like, hand to hand. Whoever gives more or asks for more has engaged in usury; the giver and receiver are the same in this regard." (Muslim). Additionally, the weight of the gold must be equal when exchanging new for used; otherwise, it involves usury. The solution is to buy the used gold with cash, then sell the new gold for cash as well. However, payment must be made at the time of the transaction in both cases. Alternatively, one could take the used gold with the intention of refining it, reshape it into a new form, or repair it, then take a fee for the workmanship or repair. And Allah Knows Best
Does Istigfar (Asking Allah for forgiveness) between the first and the second part of Friday prayer`s sermon render the prayer invalid?
Talking during Friday prayer`s sermon is disliked, but there is no harm in offering Istigfar between the two parts of the sermon, and it doesn`t invalidate the prayer as it is actually from Sunnah. And Allah Knows Best.
Is Zakah (obligatory charity) due on the items used in the trading process such as: cars , shops etc..?
No Zakah is due on equipments used in the trading process such as cars and the like.