Is the landlord's acknowledgment of extending the property lease for fifty years, without mentioning the rent value or the end date, considered a valid lease contract to which the conditions of leasing apply, especially since it contradicts custom and common practice?

If the lessor has passed away, and it is proven that the handwriting is his through the testimony of experts or the knowledge of the heirs, then this is acted upon as an extension of the previous contract. If a dispute arises, the matter is referred to the Sharia (definition) court. A written document is considered a means of proving rights in court, provided that it clearly states the right, is free from forgery, and it is proven that the handwriting is that of the writer. However, if the lessor is alive, he is most knowledgeable about his own handwriting and acknowledgment. The lease here is valid because the rent and duration are known.