The scriptures state that on Saturdays in the month of Sawan, several activities are prohibited. Such errors bring Lord Shani's anger onto oneself.
You should not buy anything iron on the final Saturday of Sawan. Don't purchase nails, iron utensils, or any other iron-based tools.
Iron Items
Don't buy anything leather on the final Saturday of Sawan. Refrain from purchasing belts, handbags, shoes, and other items made of leather.
Leather
It's also not permitted to purchase oil on the final Saturday of Sawan. Oil is donated to and offered to Shani on Saturdays. Therefore, it is forbidden to buy oil on this day.
Oil
Keep salt outside of the house. This might lead to financial difficulties in the household and resentment in relationships.
Salt
Bring nothing pointed or sharp into the house on the final Saturday of Sawan. Knives, needles, and other sharp objects should thus not be brought into the house.
Sharp objects
It is deemed improper to pick Tulsi, Durva, Belpatra, and Peepal leaves on the final Saturday of Sawan. If you think you'll need these, pick them a day ahead of time and store them.