Al Imam As Si'adi Rahimahullah mentioned in his commentary on the book Umdatul Ahkaam page 709
"And it is befitting that it is known that seeking knowledge is more virtues than it (Jihad) particularly in these times in which the scholars have become few, and in which the people have become engaged with the world, so the pursuit in seeking knowledge, then the scholars have mentioned that it is more virtues than many of the acts of worship, rather, than most of it (acts of worship), and that is in a time of it shining and abundance of the scholars and excess of that in those times, so then how about in our times in which it does not remain in it from knowledge except a little, and no sooner its banners may be wiped out, so then no doubt that seeking knowledge is more virtuous than fighting in the path of Allah, because with it is the correcting of the world, and who ever accepts upon seeking it and its acquisition, and the research in regards to its matters, then he has undertaken a great matter, and a worship, that no doubt is in this day more virtues than fighting in the path of Allah, and (more virtuous) than the prayer, and the fasting, and the hajj, and from the remaining acts of worship unrestrictedly, so if he researches he is in worship, and if he learns knowledge, or travels to seek it, or leaves to its sittings, or ponders in regards to the affairs (of knowledge), then he is in worship and the time of the one learning all of it is worship and Allah knows best"
- side note from me (majid): it should not be understood from this as some may understand it to leave off acts of worship and just seek knowledge because from seeking knowledge is acting upon your knowledge as it is said that Fudayl Ibn Iyaad Rahimahullah said: "A person with knowledge will not cease to be ignorant of what he knows until he acts upon it. So when he acts upon it, then he becomes a person with knowledge" Taken from the translation of Khateeb Al Baghdadees book Knowledge mandates action
Also what is meant in regards to the prayer, fasting and hajj is the voluntary prayer, fasting and hajj (I mention this point as this is what Shaykh Abdul Khaliq Al Wassabee hafithahullah mentioned to me when I asked him)
Also As Al Khateeb mentioned from Al Waki'a rahimahullah: "If I were to have known that the prayer is more virtuous than the hadeeth, I would have never narrated"
And what is meant here is the voluntary prayers because Khateeb mentioned this speech under the chapter of narrating is more virtuous than the voluntary prayers and it has come from Imam Ahmad that: Seeking knowledge is more virtuous than the voluntary acts of worship - as mentioned by Shaykh Al Umaysaan in Itihaaful Ibaad Page 11
Allah knows best