Shaykh and allama of shias Sharif al-Murtada said in his book “Shafi fil Imama” (1/42 – SCAN PAGE):
فأما ما حكاه عن بعضهم من أنه ” لولا الإمام لما قامت السماوات والأرض ولا صح من العبد الفعل ” . فليس نعرفه قولا لأحد من الإمامية تقدم ولا تأخر ، اللهم إلا أن يريد ما تقدم حكايته من قول الغلاة … على أن من قال بذلك من الغلاة – إن كان قاله – فلم يوجبه من حيث كان إماما ، وإنما أوجبه من حيث كان إلها
As for what he quoted from some of them that: Without the Imam the heavens and earth would not be sustained, and that worship is nullified.
We do not know anyone who held this opinion from the early or late Imamis, unless he was referring to the ghulaat(extremists)… and if one of them did say it, then he wouldn’t be make it (it refers to the quote above) a necessity in the sense of him being an Imam, but would be as such in the sense of his godly-hood.
Explanation: Al-Murtadha argues that those that said the quote above have only said it because they were ghulaat that believed that the Imams were gods.
Let us see now these non – Imamis, and ghulat.
Chief of muhadethen of shias, ibn Babaweyh al-Qummi said:
إن الحاجة إلى وجود الإمام عليه السلام إنما هو لبقاء النظام ، وقد ورد بأنه لولا الإمام لما قامت السماوات والأرض ، ولما أنزلت السماء قطرة ، ولا أخرجت الأرض بركتها
The need of existence of Imam (alaihi salam) is (fact that) by him system (of universe?) stands. And it came (in traditions) if not an imam, how heavens and earth would stand? And why sky has to reveal (rain) drops? And (without him) earth wouldn’t reveal her blessings.
Source: Burjardi “Taraif al-maqal” 2/514
Ayatollah At-Tabrizi in his book “al-Anwar al-Ilahiya fi Masail al-Akadiya” (p 174) answered to question, if walaya is condition of soundness of deeds like islam or not? This shia scholar said:
ظاهر بعض الروايات المعتبرة أنها شرط لصحة العمل ، والله العالم
Apparent from some reliable traditions that it (acceptance of walaya) is a term of soundness of deeds. And Allah knows best.
So, as we seen in the beginning, Sharif al-Murtada stressed that he didn’t hear anyone from late or early imamis, claiming that Imam is sustainer of Heaven and Earth, and he is the condition of acceptance of deeds. He also said, that these two quotes belongs to ghulat!