Martin Lings’ work is a wasiyah (legacy). If you download the PDF for free, consider it a loan. When you finish the book—and you feel that fire in your heart change the way you pray and treat your neighbors—save up to buy the physical book. Put it on your shelf next to your Quran. It is worth every rupiah.
Please note that while these resources may be available, it is essential to ensure that the PDF is downloaded from a reputable source to avoid copyright infringement.
: His dual role as a religious and political leader who unified Arab tribes and laid the foundation for Islam. Accessing the Indonesian PDF
The book you are looking for is titled (the Indonesian translation of Martin Lings' Muhammad: His Life Based on the Earliest Sources Finding the Indonesian PDF