Rif Bava Kamma 13b {29b}

13b

וחרסים כהפקר דאתי ממילא דהא איהו לא עבד ולא מידי
אבל אם נתכוין לזכות בחרסים חייב דהא לאו הפקירא נינהו
וכן הלכתא

and shared are like hefker, for they come about by themselves, for he himself did not do anything. But if he intends to merit the shards, he is liable, for behold they are not hefker. And so is the halacha.

{Bava Kamma 29b}

ומפקיר נזקיו דעלמא דלאו אנוס פלוגתא דר' יוחנן ור"א
חד אמר חייב וחד אמר פטור
[מאן דאמר פטור כרבנן] ומ"ד חייב אמר לך אנא דאמרי אפילו לרבנן דלא אמרי רבנן מפקיר נזקיו פטור אלא היכא דהוא אנוס אבל מפקיר נזקיו דעלמא חייב
ואסתיים דרבי יוחנן הוא דאמר חייב
[דאמר ר"י הלכה כסתם ותנן החופר בור ברה"ר ונפל שור לתוכו או חמור ומת חייב תסתיים]
והלכתא כוותיה

And the general case of one declaring ownerless his damaging property, it is a dispute between Rabbi Yochanan and Rabbi Eleazar. One said he is liable and one said he is exempt.
[The one who said he is exempt is like the Sages.] And the one who said he is liable may say "It is I who says these even according to the Sages. For the Sages only say that one who declares ownerless his damaging property is exempt in the case that it was accidental {that the damaging property came about}, but in the general case of declaring damaging property ownerless, he is liable.

And the conclusion is that it is Rabbi Yochanan who says he his liable. [For Rabbi Yochanan said that the halacha is like the anonymous Mishnaic ruling, and we learn {in a Mishna}: One who dug a pit in the public domain, and an ox fell into it, or a donkey, and died, he is liable. We so conclude, and the halacha is like him.

ולענין אבנו סכינו ומשאו שהניחן ברה"ר קי"ל כשמואל דאמר כולן מבורו למדנו ובכולן אני קורא בהן שור ולא אדם חמור ולא כלים
והני מילי לענין קטלא אבל לענין נזקין אדם נמי חייב וכלים פטור בין אפקרינהו בין לא אפקרינהו דכל תקלה בור הוא

And in terms of his stone, his knife, and his burden which he placed down in the public domain, we establish like Shmuel, who said that we learn all of them for his Pit, and in all of them I apply to them {from the verse in Shemot 21:33} "ox" and not man, "donkey" and not vessels. And these words are in terms of executing {something dangerous}, but in terms of {paying} damages, man is also liable and vessels are exempt, whether he declared them ownerless of did not declare them ownerless, for every nuisance is Pit.

א"ר אלעזר לא תימא נתקל באבן ונישף בה הוא דחייב אבל נתקל בקרקע ונישף באבן פטור אלא אפי' נתקל בקרקע ונישף באבן חייב כמאן כר' נתן דאמר כל היכא דליכא לאישתלומי מהאי משתלם מהאי
וכן הלכתא:

Do not suggest that it is only where the person stumbled upon the stone and the bottle broke against the stone that there is liability, but where the person stumbled because of the ground, and the bottle broke against the stone, there would be exemption. For even in the case where the person stumbled because of the ground and the bottle broke against the stone there is liability.
In accordance with who? Like Rabbi Natan, who said there wherever there is not to be paid from this one, there is to be paid from that one.
And so is the halacha.