As I discuss in this answer, one of the early movements that was important to the development of Vaishnavism was the ancient Pancharatra movement, whose sacred texts consisted of detailed procedures to worship the sage Narayana, an ancient incarnation of Vishnu. Since the Pancharatra texts originated from Narayana himself, they're followed by pretty much all Vaishnavas today. But there was a time when some people, especially those belonging to the Purva Mimamsa school, questioned the validity of the Pancharatra texts because they believed the Vedas were the only legitimate Hindu scriptures. So as I discuss in this question, the early Sri Vaishnava Acharya Yamunacharya, who was Ramanujacharya's guru's guru, composed a work called the Agama Pramanya to defend the scriptural authority of the Pancharatra texts.
Now the Purva Mimamsa school believed that Vishnu is not competent to compose a scripture (!), because he would not have the requisite knowledge to do so. So in this excerpt from the Agama Pramanya, Yamunacharya demonstrates the omniscience of Vishnu by quoting various scriptures which describe Vishnu as the supreme soul or Paramatma. Some of these scriptures are Vaishnava texts like the Vishnu Purana and the Narasimha Tapaniya Upanishad, which you'd expect to speak favorably of Vishnu. But interestingly, Yamunacharya also quotes the Linga Purana!
Likewise in the Linga Purana,
"Janardana is the sole spirit, the highest One, the Supreme Soul, from whom Brahma was born; from Him Rudra and from Him all the world." ...
Likewise in the Linga Purana,
"For there is no recourse ordained but Vishnu; this the Vedas constantly declare no doubt about it."
It's shocking to me that the Linga Purana, a quintessentially Shaiva Purana, would praise Vishnu as the supreme soul and the only recourse ordained by the Vedas.
So my question is, where exactly are these two quotes in the Linga Purana? You can read the Linga Purana through the links in my answer here.
