1. In the Hanumantsahasranam stotra, Shani is mentioned as one of the thousand names of Hanumant.
2. The Suryasanhita mentions that Hanuman was born on a Saturday (Shanivar).
3. Rudra is one of Shani’s ten names.
4. Like Shani, Hanuman too is occasionally depicted as dark complexioned.
5. In Garhval where Shani is popular, Hanuman too is depicted as wielding an iron whip. Hence, unknowingly a similarity must have been established between Shani and Hanuman. Thus leading to worship of Hanuman on Saturday and the incorporation of this worship in the vowed observance on Saturday.